Rename DomainContent -> DomainBase (#1729)

* Rename DomainContent -> DomainBase

This is a follow-up to PR #1725 which renamed DomainBase to Domain. Now, the
class naming hierarchy has the same structure as ContactBase/HostBase.

build.gradle

@@ -207,8 +207,8 @@ allprojects {
     gradle.projectsEvaluated {
       tasks.withType(JavaCompile) {
         options.fork = true
-        options.forkOptions.executable =
-            "${project.rootDir}/kythe/extractors/javac-wrapper.sh"
+        options.forkOptions.javaHome =
+          file("${System.env.REAL_JAVA_HOME}")
       }
     }
   }

core/gradle.lockfile

@@ -31,10 +31,10 @@ com.github.jnr:jnr-unixsocket:0.38.17=compileClasspath,default,deploy_jar,nonpro
 com.github.jnr:jnr-x86asm:1.0.2=compileClasspath,default,deploy_jar,nonprodCompileClasspath,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
 com.github.kevinstern:software-and-algorithms:1.0=annotationProcessor,errorprone,nonprodAnnotationProcessor,testAnnotationProcessor
 com.google.android:annotations:4.1.1.4=default,deploy_jar,nonprodRuntimeClasspath,runtimeClasspath,testRuntimeClasspath
-com.google.api-client:google-api-client-appengine:1.32.2=compileClasspath,default,deploy_jar,nonprodCompileClasspath,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
+com.google.api-client:google-api-client-appengine:1.35.2=compileClasspath,default,deploy_jar,nonprodCompileClasspath,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
 com.google.api-client:google-api-client-jackson2:1.32.2=compileClasspath,default,deploy_jar,nonprodCompileClasspath,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
 com.google.api-client:google-api-client-java6:1.35.2=compileClasspath,default,deploy_jar,nonprodCompileClasspath,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
-com.google.api-client:google-api-client-servlet:1.32.2=compileClasspath,default,deploy_jar,nonprodCompileClasspath,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
+com.google.api-client:google-api-client-servlet:1.35.2=compileClasspath,default,deploy_jar,nonprodCompileClasspath,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
 com.google.api-client:google-api-client:1.35.2=compileClasspath,default,deploy_jar,nonprodCompileClasspath,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
 com.google.api.grpc:grpc-google-cloud-bigquerystorage-v1:2.12.2=compileClasspath,default,deploy_jar,nonprodCompileClasspath,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
 com.google.api.grpc:grpc-google-cloud-bigquerystorage-v1beta1:0.136.2=compileClasspath,default,deploy_jar,nonprodCompileClasspath,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
@@ -90,13 +90,12 @@ com.google.apis:google-api-services-pubsub:v1-rev20211130-1.32.1=compileClasspat
 com.google.apis:google-api-services-sheets:v4-rev20220620-1.32.1=compileClasspath,default,deploy_jar,nonprodCompileClasspath,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
 com.google.apis:google-api-services-sqladmin:v1beta4-rev20220623-1.32.1=compileClasspath,default,deploy_jar,nonprodCompileClasspath,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
 com.google.apis:google-api-services-storage:v1-rev20220705-1.32.1=compileClasspath,default,deploy_jar,nonprodCompileClasspath,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
-com.google.appengine.tools:appengine-gcs-client:0.8.3=compileClasspath,default,deploy_jar,nonprodCompileClasspath,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
+com.google.appengine.tools:appengine-gcs-client:0.8.1=compileClasspath,default,deploy_jar,nonprodCompileClasspath,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
 com.google.appengine.tools:appengine-pipeline:0.2.13=compileClasspath,default,deploy_jar,nonprodCompileClasspath,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
 com.google.appengine:appengine-api-1.0-sdk:2.0.5=compileClasspath,default,deploy_jar,nonprodCompileClasspath,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
-com.google.appengine:appengine-api-stubs:2.0.5=default,deploy_jar,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
+com.google.appengine:appengine-api-stubs:2.0.5=testCompileClasspath,testRuntimeClasspath
 com.google.appengine:appengine-remote-api:2.0.5=compileClasspath,default,deploy_jar,nonprodCompileClasspath,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
-com.google.appengine:appengine-testing:2.0.5=default,deploy_jar,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
-com.google.appengine:appengine-tools-sdk:2.0.5=default,deploy_jar,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
+com.google.appengine:appengine-testing:1.9.86=default,deploy_jar,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
 com.google.auth:google-auth-library-credentials:1.8.0=compileClasspath,default,deploy_jar,nonprodCompileClasspath,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
 com.google.auth:google-auth-library-oauth2-http:1.8.0=compileClasspath,default,deploy_jar,nonprodCompileClasspath,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
 com.google.auto.service:auto-service-annotations:1.0.1=annotationProcessor,compileClasspath,default,deploy_jar,nonprodCompileClasspath,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
@@ -300,7 +299,7 @@ javax.validation:validation-api:1.0.0.GA=compileClasspath,default,deploy_jar,non
 javax.xml.bind:jaxb-api:2.3.1=compileClasspath,default,deploy_jar,nonprodCompileClasspath,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
 javax.xml.bind:jaxb-api:2.4.0-b180830.0359=jaxb
 jline:jline:1.0=compileClasspath,default,deploy_jar,nonprodCompileClasspath,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
-joda-time:joda-time:2.10.13=compileClasspath,default,deploy_jar,nonprodCompileClasspath,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
+joda-time:joda-time:2.10.10=compileClasspath,default,deploy_jar,nonprodCompileClasspath,nonprodRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
 junit:junit:4.13.2=default,nonprodCompileClasspath,nonprodRuntimeClasspath,testCompileClasspath,testRuntimeClasspath
 net.arnx:nashorn-promise:0.1.1=nonprodRuntime,runtime,testRuntimeClasspath
 net.bytebuddy:byte-buddy-agent:1.12.10=testCompileClasspath,testRuntimeClasspath

core/src/main/java/google/registry/batch/DeleteExpiredDomainsAction.java

@@ -32,7 +32,7 @@ import google.registry.flows.EppController;
 import google.registry.flows.EppRequestSource;
 import google.registry.flows.PasswordOnlyTransportCredentials;
 import google.registry.flows.StatelessRequestSessionMetadata;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.eppcommon.ProtocolDefinition;
 import google.registry.model.eppoutput.EppOutput;
 import google.registry.persistence.transaction.QueryComposer.Comparator;
@@ -128,10 +128,10 @@ public class DeleteExpiredDomainsAction implements Runnable {
     logger.atInfo().log(
         "Deleting non-renewing domains with autorenew end times up through %s.", runTime);
 
-    ImmutableList<DomainBase> domainsToDelete =
+    ImmutableList<Domain> domainsToDelete =
         tm().transact(
                 () ->
-                    tm().createQueryComposer(DomainBase.class)
+                    tm().createQueryComposer(Domain.class)
                         .where("autorenewEndTime", Comparator.LTE, runTime)
                         .where("deletionTime", Comparator.EQ, END_OF_TIME)
                         .list());
@@ -145,10 +145,9 @@ public class DeleteExpiredDomainsAction implements Runnable {
         "Found %d domains to delete: %s.",
         domainsToDelete.size(),
         String.join(
-            ", ",
-            domainsToDelete.stream().map(DomainBase::getDomainName).collect(toImmutableList())));
+            ", ", domainsToDelete.stream().map(Domain::getDomainName).collect(toImmutableList())));
     int successes = 0;
-    for (DomainBase domain : domainsToDelete) {
+    for (Domain domain : domainsToDelete) {
       if (runDomainDeleteFlow(domain)) {
         successes++;
       }
@@ -163,7 +162,7 @@ public class DeleteExpiredDomainsAction implements Runnable {
   }
 
   /** Runs the actual domain delete flow and returns whether the deletion was successful. */
-  private boolean runDomainDeleteFlow(DomainBase domain) {
+  private boolean runDomainDeleteFlow(Domain domain) {
     logger.atInfo().log("Attempting to delete domain '%s'.", domain.getDomainName());
     // Create a new transaction that the flow's execution will be enlisted in that loads the domain
     // transactionally. This way we can ensure that nothing else has modified the domain in question
@@ -171,7 +170,7 @@ public class DeleteExpiredDomainsAction implements Runnable {
     Optional<EppOutput> eppOutput =
         tm().transact(
                 () -> {
-                  DomainBase transDomain = tm().loadByKey(domain.createVKey());
+                  Domain transDomain = tm().loadByKey(domain.createVKey());
                   if (!domain.getAutorenewEndTime().isPresent()
                       || domain.getAutorenewEndTime().get().isAfter(tm().getTransactionTime())) {
                     logger.atSevere().log(

core/src/main/java/google/registry/batch/DeleteLoadTestDataAction.java

@@ -30,7 +30,7 @@ import google.registry.flows.poll.PollFlowUtils;
 import google.registry.model.EppResource;
 import google.registry.model.EppResourceUtils;
 import google.registry.model.contact.ContactResource;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.host.HostResource;
 import google.registry.model.poll.PollMessage;
 import google.registry.model.reporting.HistoryEntry;
@@ -129,7 +129,7 @@ public class DeleteLoadTestDataAction implements Runnable {
     }
     VKey<HostResource> hostVKey = host.createVKey();
     // We can remove hosts from linked domains, so we should do so then delete the hosts
-    ImmutableSet<VKey<DomainBase>> linkedDomains =
+    ImmutableSet<VKey<Domain>> linkedDomains =
         EppResourceUtils.getLinkedDomainKeys(hostVKey, clock.nowUtc(), null);
     tm().loadByKeys(linkedDomains)
         .values()

core/src/main/java/google/registry/batch/DeleteProberDataAction.java

@@ -37,7 +37,7 @@ import google.registry.config.RegistryEnvironment;
 import google.registry.dns.DnsQueue;
 import google.registry.model.CreateAutoTimestamp;
 import google.registry.model.EppResourceUtils;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainHistory;
 import google.registry.model.tld.Registry.TldType;
 import google.registry.request.Action;
@@ -53,8 +53,8 @@ import org.joda.time.DateTime;
 import org.joda.time.Duration;
 
 /**
- * Deletes all prober DomainBases and their subordinate history entries, poll messages, and billing
- * events, along with their ForeignKeyDomainIndex and EppResourceIndex entities.
+ * Deletes all prober {@link Domain}s and their subordinate history entries, poll messages, and
+ * billing events, along with their ForeignKeyDomainIndex and EppResourceIndex entities.
  */
 @Action(
     service = Action.Service.BACKEND,
@@ -154,7 +154,7 @@ public class DeleteProberDataAction implements Runnable {
     // keeping track of which domains to hard-delete (there can be many, so we batch them up)
     ScrollableResults scrollableResult =
         jpaTm()
-            .query(DOMAIN_QUERY_STRING, DomainBase.class)
+            .query(DOMAIN_QUERY_STRING, Domain.class)
             .setParameter("tlds", deletableTlds)
             .setParameter(
                 "creationTimeCutoff", CreateAutoTimestamp.create(now.minus(DOMAIN_USED_DURATION)))
@@ -166,7 +166,7 @@ public class DeleteProberDataAction implements Runnable {
     ImmutableList.Builder<String> domainRepoIdsToHardDelete = new ImmutableList.Builder<>();
     ImmutableList.Builder<String> hostNamesToHardDelete = new ImmutableList.Builder<>();
     for (int i = 1; scrollableResult.next(); i = (i + 1) % BATCH_SIZE) {
-      DomainBase domain = (DomainBase) scrollableResult.get(0);
+      Domain domain = (Domain) scrollableResult.get(0);
       processDomain(
           domain,
           domainRepoIdsToHardDelete,
@@ -187,7 +187,7 @@ public class DeleteProberDataAction implements Runnable {
   }
 
   private void processDomain(
-      DomainBase domain,
+      Domain domain,
       ImmutableList.Builder<String> domainRepoIdsToHardDelete,
       ImmutableList.Builder<String> hostNamesToHardDelete,
       AtomicInteger softDeletedDomains,
@@ -251,8 +251,8 @@ public class DeleteProberDataAction implements Runnable {
   }
 
   // Take a DNS queue + admin registrar id as input so that it can be called from the mapper as well
-  private void softDeleteDomain(DomainBase domain) {
-    DomainBase deletedDomain =
+  private void softDeleteDomain(Domain domain) {
+    Domain deletedDomain =
         domain.asBuilder().setDeletionTime(tm().getTransactionTime()).setStatusValues(null).build();
     DomainHistory historyEntry =
         new DomainHistory.Builder()
@@ -266,7 +266,7 @@ public class DeleteProberDataAction implements Runnable {
     // Note that we don't bother handling grace periods, billing events, pending transfers, poll
     // messages, or auto-renews because those will all be hard-deleted the next time the job runs
     // anyway.
-    tm().putAllWithoutBackup(ImmutableList.of(deletedDomain, historyEntry));
+    tm().putAll(ImmutableList.of(deletedDomain, historyEntry));
     // updating foreign keys is a no-op in SQL
     updateForeignKeyIndexDeletionTime(deletedDomain);
     dnsQueue.addDomainRefreshTask(deletedDomain.getDomainName());

core/src/main/java/google/registry/batch/ExpandRecurringBillingEventsAction.java

@@ -43,7 +43,7 @@ import google.registry.model.billing.BillingEvent.Flag;
 import google.registry.model.billing.BillingEvent.OneTime;
 import google.registry.model.billing.BillingEvent.Recurring;
 import google.registry.model.common.Cursor;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainHistory;
 import google.registry.model.domain.Period;
 import google.registry.model.reporting.DomainTransactionRecord;
@@ -253,9 +253,7 @@ public class ExpandRecurringBillingEventsAction implements Runnable {
     final ImmutableSet<DateTime> billingTimes =
         getBillingTimesInScope(eventTimes, cursorTime, executeTime, tld);
 
-    VKey<DomainBase> domainKey =
-        VKey.create(
-            DomainBase.class, recurring.getDomainRepoId(), recurring.getParentKey().getParent());
+    VKey<Domain> domainKey = VKey.createSql(Domain.class, recurring.getDomainRepoId());
     Iterable<OneTime> oneTimesForDomain;
     oneTimesForDomain =
         tm().createQueryComposer(OneTime.class)
@@ -311,11 +309,11 @@ public class ExpandRecurringBillingEventsAction implements Runnable {
                       .getRenewCost())
               .setEventTime(eventTime)
               .setFlags(union(recurring.getFlags(), Flag.SYNTHETIC))
-              .setParent(historyEntry)
+              .setDomainHistory(historyEntry)
               .setPeriodYears(1)
               .setReason(recurring.getReason())
               .setSyntheticCreationTime(executeTime)
-              .setCancellationMatchingBillingEvent(recurring.createVKey())
+              .setCancellationMatchingBillingEvent(recurring)
               .setTargetId(recurring.getTargetId())
               .build());
     }

core/src/main/java/google/registry/batch/RelockDomainAction.java

@@ -27,7 +27,7 @@ import com.google.common.collect.ImmutableSet;
 import com.google.common.flogger.FluentLogger;
 import com.google.common.net.MediaType;
 import google.registry.config.RegistryConfig.Config;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.RegistryLock;
 import google.registry.model.eppcommon.StatusValue;
 import google.registry.model.registrar.Registrar;
@@ -125,7 +125,7 @@ public class RelockDomainAction implements Runnable {
 
   private void relockDomain() {
     RegistryLock oldLock = null;
-    DomainBase domain;
+    Domain domain;
     try {
       oldLock =
           RegistryLockDao.getByRevisionId(oldUnlockRevisionId)
@@ -134,7 +134,7 @@ public class RelockDomainAction implements Runnable {
                       new IllegalArgumentException(
                           String.format("Unknown revision ID %d", oldUnlockRevisionId)));
       domain =
-          tm().loadByKey(VKey.create(DomainBase.class, oldLock.getRepoId()))
+          tm().loadByKey(VKey.create(Domain.class, oldLock.getRepoId()))
               .cloneProjectedAtTime(tm().getTransactionTime());
     } catch (Throwable t) {
       handleTransientFailure(Optional.ofNullable(oldLock), t);
@@ -180,7 +180,7 @@ public class RelockDomainAction implements Runnable {
     }
   }
 
-  private void verifyDomainAndLockState(RegistryLock oldLock, DomainBase domain) {
+  private void verifyDomainAndLockState(RegistryLock oldLock, Domain domain) {
     // Domain shouldn't be deleted or have a pending transfer/delete
     String domainName = domain.getDomainName();
     ImmutableSet<StatusValue> statusValues = domain.getStatusValues();

core/src/main/java/google/registry/beam/common/RegistryPipelineComponent.java

@@ -20,6 +20,7 @@ import dagger.Lazy;
 import google.registry.config.CredentialModule;
 import google.registry.config.RegistryConfig.Config;
 import google.registry.config.RegistryConfig.ConfigModule;
+import google.registry.model.domain.Domain;
 import google.registry.persistence.PersistenceModule;
 import google.registry.persistence.PersistenceModule.BeamBulkQueryJpaTm;
 import google.registry.persistence.PersistenceModule.BeamJpaTm;
@@ -53,8 +54,7 @@ public interface RegistryPipelineComponent {
 
   /**
    * Returns a {@link JpaTransactionManager} optimized for bulk loading multi-level JPA entities
-   * ({@link google.registry.model.domain.DomainBase} and {@link
-   * google.registry.model.domain.DomainHistory}). Please refer to {@link
+   * ({@link Domain} and {@link google.registry.model.domain.DomainHistory}). Please refer to {@link
    * google.registry.model.bulkquery.BulkQueryEntities} for more information.
    */
   @BeamBulkQueryJpaTm

core/src/main/java/google/registry/beam/invoicing/BillingEvent.java

@@ -14,47 +14,38 @@
 
 package google.registry.beam.invoicing;
 
-import static google.registry.beam.BeamUtils.checkFieldsNotNull;
-import static google.registry.beam.BeamUtils.extractField;
-
 import com.google.auto.value.AutoValue;
-import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Joiner;
 import com.google.common.collect.ImmutableList;
-import google.registry.model.billing.BillingEvent.Flag;
 import google.registry.reporting.billing.BillingModule;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.io.Serializable;
-import java.text.DecimalFormat;
-import java.util.stream.Collectors;
-import org.apache.avro.generic.GenericRecord;
+import java.util.regex.Pattern;
 import org.apache.beam.sdk.coders.AtomicCoder;
 import org.apache.beam.sdk.coders.Coder;
 import org.apache.beam.sdk.coders.StringUtf8Coder;
-import org.apache.beam.sdk.io.gcp.bigquery.SchemaAndRecord;
 import org.joda.time.DateTime;
-import org.joda.time.DateTimeZone;
 import org.joda.time.format.DateTimeFormat;
 import org.joda.time.format.DateTimeFormatter;
 
 /**
  * A POJO representing a single billable event, parsed from a {@code SchemaAndRecord}.
  *
- * <p>This is a trivially serializable class that allows Beam to transform the results of a Bigquery
- * query into a standard Java representation, giving us the type guarantees and ease of manipulation
- * Bigquery lacks, while localizing any Bigquery-side failures to the {@link #parseFromRecord}
- * function.
+ * <p>This is a trivially serializable class that allows Beam to transform the results of a Cloud
+ * SQL query into a standard Java representation, giving us the type guarantees and ease of
+ * manipulation Cloud SQL lacks.
  */
 @AutoValue
 public abstract class BillingEvent implements Serializable {
 
+  private static final long serialVersionUID = -3593088371541450077L;
+
   private static final DateTimeFormatter DATE_TIME_FORMATTER =
       DateTimeFormat.forPattern("yyyy-MM-dd HH:mm:ss zzz");
 
-  /** The amount we multiply the price for sunrise creates. This is currently a 15% discount. */
-  private static final double SUNRISE_DISCOUNT_PRICE_MODIFIER = 0.85;
+  private static final Pattern SYNTHETIC_REGEX = Pattern.compile("SYNTHETIC", Pattern.LITERAL);
 
   private static final ImmutableList<String> FIELD_NAMES =
       ImmutableList.of(
@@ -115,67 +106,7 @@ public abstract class BillingEvent implements Serializable {
   /** Returns a list of space-delimited flags associated with the event. */
   abstract String flags();
 
-  /**
-   * Constructs a {@code BillingEvent} from a {@code SchemaAndRecord}.
-   *
-   * @see <a
-   *     href=http://avro.apache.org/docs/1.7.7/api/java/org/apache/avro/generic/GenericData.Record.html>
-   *     Apache AVRO GenericRecord</a>
-   */
-  static BillingEvent parseFromRecord(SchemaAndRecord schemaAndRecord) {
-    checkFieldsNotNull(FIELD_NAMES, schemaAndRecord);
-    GenericRecord record = schemaAndRecord.getRecord();
-    String flags = extractField(record, "flags");
-    double amount = getDiscountedAmount(Double.parseDouble(extractField(record, "amount")), flags);
-    return create(
-        // We need to chain parsers off extractField because GenericRecord only returns
-        // Objects, which contain a string representation of their underlying types.
-        Long.parseLong(extractField(record, "id")),
-        // Bigquery provides UNIX timestamps with microsecond precision.
-        new DateTime(Long.parseLong(extractField(record, "billingTime")) / 1000, DateTimeZone.UTC),
-        new DateTime(Long.parseLong(extractField(record, "eventTime")) / 1000, DateTimeZone.UTC),
-        extractField(record, "registrarId"),
-        extractField(record, "billingId"),
-        extractField(record, "poNumber"),
-        extractField(record, "tld"),
-        extractField(record, "action"),
-        extractField(record, "domain"),
-        extractField(record, "repositoryId"),
-        Integer.parseInt(extractField(record, "years")),
-        extractField(record, "currency"),
-        amount,
-        flags);
-  }
-
-  /**
-   * Applies a discount to sunrise creates and anchor tenant creates if applicable.
-   *
-   * Currently sunrise creates are discounted 15% and anchor tenant creates are free for 2 years.
-   * All anchor tenant creates are enforced to be 2 years in
-   * {@link google.registry.flows.domain.DomainCreateFlow#verifyAnchorTenantValidPeriod}.
-   */
-  private static double getDiscountedAmount(double amount, String flags) {
-    // Apply a configurable discount to sunrise creates.
-    if (flags.contains(Flag.SUNRISE.name())) {
-      amount =
-          Double.parseDouble(
-              new DecimalFormat("#.##").format(amount * SUNRISE_DISCOUNT_PRICE_MODIFIER));
-    }
-    // Anchor tenant creates are free for the initial create. This is enforced to be a 2 year period
-    // upon domain create.
-    if (flags.contains(Flag.ANCHOR_TENANT.name())) {
-      amount = 0;
-    }
-    return amount;
-  }
-
-  /**
-   * Creates a concrete {@code BillingEvent}.
-   *
-   * <p>This should only be used outside this class for testing- instances of {@code BillingEvent}
-   * should otherwise come from {@link #parseFromRecord}.
-   */
-  @VisibleForTesting
+  /** Creates a concrete {@link BillingEvent}. */
   static BillingEvent create(
       long id,
       DateTime billingTime,
@@ -209,7 +140,7 @@ public abstract class BillingEvent implements Serializable {
   }
 
   static String getHeader() {
-    return FIELD_NAMES.stream().collect(Collectors.joining(","));
+    return String.join(",", FIELD_NAMES);
   }
 
   /**
@@ -242,7 +173,7 @@ public abstract class BillingEvent implements Serializable {
                 currency(),
                 String.format("%.2f", amount()),
                 // Strip out the 'synthetic' flag, which is internal only.
-                flags().replace("SYNTHETIC", "").trim()));
+                SYNTHETIC_REGEX.matcher(flags()).replaceAll("").trim()));
   }
 
   /** Returns the grouping key for this {@code BillingEvent}, to generate the overall invoice. */
@@ -274,6 +205,8 @@ public abstract class BillingEvent implements Serializable {
   @AutoValue
   abstract static class InvoiceGroupingKey implements Serializable {
 
+    private static final long serialVersionUID = -151561764235256205L;
+
     private static final ImmutableList<String> INVOICE_HEADERS =
         ImmutableList.of(
             "StartDate",
@@ -345,6 +278,8 @@ public abstract class BillingEvent implements Serializable {
     /** Coder that provides deterministic (de)serialization for {@code InvoiceGroupingKey}. */
     static class InvoiceGroupingKeyCoder extends AtomicCoder<InvoiceGroupingKey> {
 
+      private static final long serialVersionUID = 6680701524304107547L;
+
       @Override
       public void encode(InvoiceGroupingKey value, OutputStream outStream) throws IOException {
         Coder<String> stringCoder = StringUtf8Coder.of();

core/src/main/java/google/registry/beam/invoicing/InvoicingPipeline.java

@@ -24,16 +24,14 @@ import google.registry.beam.common.RegistryJpaIO.Read;
 import google.registry.beam.invoicing.BillingEvent.InvoiceGroupingKey;
 import google.registry.beam.invoicing.BillingEvent.InvoiceGroupingKey.InvoiceGroupingKeyCoder;
 import google.registry.model.billing.BillingEvent.Flag;
+import google.registry.model.billing.BillingEvent.OneTime;
 import google.registry.model.registrar.Registrar;
 import google.registry.persistence.PersistenceModule.TransactionIsolationLevel;
 import google.registry.reporting.billing.BillingModule;
 import google.registry.util.DomainNameUtils;
 import google.registry.util.SqlTemplate;
 import java.io.Serializable;
-import java.time.LocalDateTime;
-import java.time.LocalTime;
 import java.time.YearMonth;
-import java.time.format.DateTimeFormatter;
 import java.util.Objects;
 import java.util.Optional;
 import java.util.regex.Pattern;
@@ -66,8 +64,7 @@ import org.joda.money.CurrencyUnit;
  */
 public class InvoicingPipeline implements Serializable {
 
-  private static final DateTimeFormatter TIMESTAMP_FORMATTER =
-      DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSSSSS");
+  private static final long serialVersionUID = 5386330443625580081L;
 
   private static final Pattern SQL_COMMENT_REGEX =
       Pattern.compile("^\\s*--.*\\n", Pattern.MULTILINE);
@@ -107,8 +104,7 @@ public class InvoicingPipeline implements Serializable {
   }
 
   private static Optional<BillingEvent> parseRow(Object[] row) {
-    google.registry.model.billing.BillingEvent.OneTime oneTime =
-        (google.registry.model.billing.BillingEvent.OneTime) row[0];
+    OneTime oneTime = (OneTime) row[0];
     Registrar registrar = (Registrar) row[1];
     CurrencyUnit currency = oneTime.getCost().getCurrencyUnit();
     if (!registrar.getBillingAccountMap().containsKey(currency)) {
@@ -140,6 +136,9 @@ public class InvoicingPipeline implements Serializable {
   /** Transform that converts a {@code BillingEvent} into an invoice CSV row. */
   private static class GenerateInvoiceRows
       extends PTransform<PCollection<BillingEvent>, PCollection<String>> {
+
+    private static final long serialVersionUID = -8090619008258393728L;
+
     @Override
     public PCollection<String> expand(PCollection<BillingEvent> input) {
       return input
@@ -203,32 +202,13 @@ public class InvoicingPipeline implements Serializable {
                 TextIO.sink().withHeader(BillingEvent.getHeader())));
   }
 
-  /** Create the Bigquery query for a given project and yearMonth at runtime. */
-  static String makeQuery(String yearMonth, String projectId) {
-    // Get the timestamp endpoints capturing the entire month with microsecond precision
-    YearMonth reportingMonth = YearMonth.parse(yearMonth);
-    LocalDateTime firstMoment = reportingMonth.atDay(1).atTime(LocalTime.MIDNIGHT);
-    LocalDateTime lastMoment = reportingMonth.atEndOfMonth().atTime(LocalTime.MAX);
-    // Construct the month's query by filling in the billing_events.sql template
-    return SqlTemplate.create(getQueryFromFile(InvoicingPipeline.class, "billing_events.sql"))
-        .put("FIRST_TIMESTAMP_OF_MONTH", firstMoment.format(TIMESTAMP_FORMATTER))
-        .put("LAST_TIMESTAMP_OF_MONTH", lastMoment.format(TIMESTAMP_FORMATTER))
-        .put("PROJECT_ID", projectId)
-        .put("DATASTORE_EXPORT_DATA_SET", "latest_datastore_export")
-        .put("ONETIME_TABLE", "OneTime")
-        .put("REGISTRY_TABLE", "Registry")
-        .put("REGISTRAR_TABLE", "Registrar")
-        .put("CANCELLATION_TABLE", "Cancellation")
-        .build();
-  }
-
   /** Create the Cloud SQL query for a given yearMonth at runtime. */
   static String makeCloudSqlQuery(String yearMonth) {
     YearMonth endMonth = YearMonth.parse(yearMonth).plusMonths(1);
     String queryWithComments =
         SqlTemplate.create(
                 getQueryFromFile(InvoicingPipeline.class, "cloud_sql_billing_events.sql"))
-            .put("FIRST_TIMESTAMP_OF_MONTH", yearMonth.concat("-01"))
+            .put("FIRST_TIMESTAMP_OF_MONTH", yearMonth + "-01")
             .put(
                 "LAST_TIMESTAMP_OF_MONTH",
                 String.format("%d-%d-01", endMonth.getYear(), endMonth.getMonthValue()))

core/src/main/java/google/registry/beam/rde/RdePipeline.java

@@ -47,7 +47,7 @@ import google.registry.gcs.GcsUtils;
 import google.registry.model.EppResource;
 import google.registry.model.contact.ContactHistory;
 import google.registry.model.contact.ContactResource;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainHistory;
 import google.registry.model.host.HostHistory;
 import google.registry.model.host.HostResource;
@@ -132,7 +132,7 @@ import org.joda.time.DateTime;
  * that are soft-deleted by watermark. The history is emitted as pairs of (resource repo ID: history
  * revision ID) from the SQL query.
  *
- * <h3>{@link DomainBase}</h3>
+ * <h3>{@link Domain}</h3>
  *
  * After the most recent (live) domain resources are loaded from the corresponding history objects,
  * we marshall them to deposit fragments and emit the (pending deposit: deposit fragment) pairs for
@@ -195,7 +195,7 @@ public class RdePipeline implements Serializable {
   private static final ImmutableMap<Class<? extends HistoryEntry>, String> EPP_RESOURCE_FIELD_NAME =
       ImmutableMap.of(
           DomainHistory.class,
-          "domainContent",
+          "domainBase",
           ContactHistory.class,
           "contactBase",
           HostHistory.class,
@@ -477,8 +477,8 @@ public class RdePipeline implements Serializable {
                   public void processElement(
                       @Element KV<String, Long> kv, MultiOutputReceiver receiver) {
                     activeDomainCounter.inc();
-                    DomainBase domain =
-                        (DomainBase)
+                    Domain domain =
+                        (Domain)
                             loadResourceByHistoryEntryId(
                                 DomainHistory.class, kv.getKey(), kv.getValue());
                     pendingDeposits.stream()
@@ -654,8 +654,8 @@ public class RdePipeline implements Serializable {
                         TypeDescriptor.of(DepositFragment.class)))
                 .via(
                     (KV<String, CoGbkResult> kv) -> {
-                      DomainBase superordinateDomain =
-                          (DomainBase)
+                      Domain superordinateDomain =
+                          (Domain)
                               loadResourceByHistoryEntryId(
                                   DomainHistory.class,
                                   kv.getKey(),

core/src/main/java/google/registry/beam/resave/ResaveAllEppResourcesPipeline.java

@@ -23,6 +23,7 @@ import google.registry.beam.common.RegistryJpaIO;
 import google.registry.beam.common.RegistryJpaIO.Read;
 import google.registry.model.EppResource;
 import google.registry.model.contact.ContactResource;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainBase;
 import google.registry.model.host.HostResource;
 import google.registry.persistence.PersistenceModule.TransactionIsolationLevel;
@@ -51,7 +52,7 @@ import org.joda.time.DateTime;
 public class ResaveAllEppResourcesPipeline implements Serializable {
 
   private static final ImmutableSet<Class<? extends EppResource>> EPP_RESOURCE_CLASSES =
-      ImmutableSet.of(ContactResource.class, DomainBase.class, HostResource.class);
+      ImmutableSet.of(ContactResource.class, Domain.class, HostResource.class);
 
   /**
    * There exist three possible situations where we know we'll want to project domains to the
@@ -111,16 +112,16 @@ public class ResaveAllEppResourcesPipeline implements Serializable {
    * transfers, grace periods).
    *
    * <p>The logic of what might have changed is paraphrased from {@link
-   * google.registry.model.domain.DomainContent#cloneProjectedAtTime(DateTime)}.
+   * DomainBase#cloneProjectedAtTime(DateTime)}.
    */
   private void fastResaveDomains(Pipeline pipeline) {
-    Read<DomainBase, DomainBase> read =
+    Read<Domain, Domain> read =
         RegistryJpaIO.read(
             DOMAINS_TO_PROJECT_QUERY,
             ImmutableMap.of("END_OF_TIME", DateTimeUtils.END_OF_TIME),
-            DomainBase.class,
+            Domain.class,
             d -> d);
-    projectAndResaveResources(pipeline, DomainBase.class, read);
+    projectAndResaveResources(pipeline, Domain.class, read);
   }
 
   /** Projects all resources to the current time and saves them. */

core/src/main/java/google/registry/beam/spec11/Spec11Pipeline.java

@@ -26,7 +26,7 @@ import google.registry.beam.common.RegistryJpaIO;
 import google.registry.beam.common.RegistryJpaIO.Read;
 import google.registry.beam.spec11.SafeBrowsingTransforms.EvaluateSafeBrowsingFn;
 import google.registry.config.RegistryConfig.ConfigModule;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.reporting.Spec11ThreatMatch;
 import google.registry.model.reporting.Spec11ThreatMatch.ThreatType;
 import google.registry.persistence.PersistenceModule.TransactionIsolationLevel;
@@ -127,22 +127,21 @@ public class Spec11Pipeline implements Serializable {
                   @ProcessElement
                   public void processElement(
                       @Element KV<String, String> input, OutputReceiver<DomainNameInfo> output) {
-                    DomainBase domainBase =
+                    Domain domain =
                         jpaTm()
                             .transact(
                                 () ->
                                     jpaTm()
-                                        .loadByKey(
-                                            VKey.createSql(DomainBase.class, input.getKey())));
+                                        .loadByKey(VKey.createSql(Domain.class, input.getKey())));
                     String emailAddress = input.getValue();
                     if (emailAddress == null) {
                       emailAddress = "";
                     }
                     DomainNameInfo domainNameInfo =
                         DomainNameInfo.create(
-                            domainBase.getDomainName(),
-                            domainBase.getRepoId(),
-                            domainBase.getCurrentSponsorRegistrarId(),
+                            domain.getDomainName(),
+                            domain.getRepoId(),
+                            domain.getCurrentSponsorRegistrarId(),
                             emailAddress);
                     output.output(domainNameInfo);
                   }

core/src/main/java/google/registry/dns/RefreshDnsAction.java

@@ -20,7 +20,7 @@ import google.registry.dns.DnsConstants.TargetType;
 import google.registry.model.EppResource;
 import google.registry.model.EppResource.ForeignKeyedEppResource;
 import google.registry.model.annotations.ExternalMessagingName;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.host.HostResource;
 import google.registry.request.Action;
 import google.registry.request.HttpException.BadRequestException;
@@ -62,7 +62,7 @@ public final class RefreshDnsAction implements Runnable {
     }
     switch (type) {
       case DOMAIN:
-        loadAndVerifyExistence(DomainBase.class, domainOrHostName);
+        loadAndVerifyExistence(Domain.class, domainOrHostName);
         dnsQueue.addDomainRefreshTask(domainOrHostName);
         break;
       case HOST:

core/src/main/java/google/registry/dns/writer/clouddns/CloudDnsWriter.java

@@ -36,7 +36,7 @@ import google.registry.config.RegistryConfig.Config;
 import google.registry.dns.writer.BaseDnsWriter;
 import google.registry.dns.writer.DnsWriter;
 import google.registry.dns.writer.DnsWriterZone;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.secdns.DelegationSignerData;
 import google.registry.model.host.HostResource;
 import google.registry.model.tld.Registries;
@@ -121,13 +121,12 @@ public class CloudDnsWriter extends BaseDnsWriter {
     String absoluteDomainName = getAbsoluteHostName(domainName);
 
     // Load the target domain. Note that it can be absent if this domain was just deleted.
-    Optional<DomainBase> domainBase =
-        loadByForeignKey(DomainBase.class, domainName, clock.nowUtc());
+    Optional<Domain> domain = loadByForeignKey(Domain.class, domainName, clock.nowUtc());
 
     // Return early if no DNS records should be published.
     // desiredRecordsBuilder is populated with an empty set to indicate that all existing records
     // should be deleted.
-    if (!domainBase.isPresent() || !domainBase.get().shouldPublishToDns()) {
+    if (!domain.isPresent() || !domain.get().shouldPublishToDns()) {
       desiredRecords.put(absoluteDomainName, ImmutableSet.of());
       return;
     }
@@ -135,7 +134,7 @@ public class CloudDnsWriter extends BaseDnsWriter {
     ImmutableSet.Builder<ResourceRecordSet> domainRecords = new ImmutableSet.Builder<>();
 
     // Construct DS records (if any).
-    Set<DelegationSignerData> dsData = domainBase.get().getDsData();
+    Set<DelegationSignerData> dsData = domain.get().getDsData();
     if (!dsData.isEmpty()) {
       HashSet<String> dsRrData = new HashSet<>();
       for (DelegationSignerData ds : dsData) {
@@ -154,8 +153,8 @@ public class CloudDnsWriter extends BaseDnsWriter {
     }
 
     // Construct NS records (if any).
-    Set<String> nameserverData = domainBase.get().loadNameserverHostNames();
-    Set<String> subordinateHosts = domainBase.get().getSubordinateHosts();
+    Set<String> nameserverData = domain.get().loadNameserverHostNames();
+    Set<String> subordinateHosts = domain.get().getSubordinateHosts();
     if (!nameserverData.isEmpty()) {
       HashSet<String> nsRrData = new HashSet<>();
       for (String hostName : nameserverData) {

core/src/main/java/google/registry/dns/writer/dnsupdate/DnsUpdateWriter.java

@@ -27,7 +27,7 @@ import com.google.common.net.InternetDomainName;
 import google.registry.config.RegistryConfig.Config;
 import google.registry.dns.writer.BaseDnsWriter;
 import google.registry.dns.writer.DnsWriterZone;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.secdns.DelegationSignerData;
 import google.registry.model.host.HostResource;
 import google.registry.model.tld.Registries;
@@ -127,12 +127,11 @@ public class DnsUpdateWriter extends BaseDnsWriter {
    *     this domain refresh request
    */
   private void publishDomain(String domainName, String requestingHostName) {
-    Optional<DomainBase> domainOptional =
-        loadByForeignKey(DomainBase.class, domainName, clock.nowUtc());
+    Optional<Domain> domainOptional = loadByForeignKey(Domain.class, domainName, clock.nowUtc());
     update.delete(toAbsoluteName(domainName), Type.ANY);
     // If the domain is now deleted, then don't update DNS for it.
     if (domainOptional.isPresent()) {
-      DomainBase domain = domainOptional.get();
+      Domain domain = domainOptional.get();
       // As long as the domain exists, orphan glues should be cleaned.
       deleteSubordinateHostAddressSet(domain, requestingHostName, update);
       if (domain.shouldPublishToDns()) {
@@ -184,7 +183,7 @@ public class DnsUpdateWriter extends BaseDnsWriter {
     }
   }
 
-  private RRset makeDelegationSignerSet(DomainBase domain) {
+  private RRset makeDelegationSignerSet(Domain domain) {
     RRset signerSet = new RRset();
     for (DelegationSignerData signerData : domain.getDsData()) {
       DSRecord dsRecord =
@@ -202,7 +201,7 @@ public class DnsUpdateWriter extends BaseDnsWriter {
   }
 
   private void deleteSubordinateHostAddressSet(
-      DomainBase domain, String additionalHost, Update update) {
+      Domain domain, String additionalHost, Update update) {
     for (String hostName :
         union(
             domain.getSubordinateHosts(),
@@ -213,7 +212,7 @@ public class DnsUpdateWriter extends BaseDnsWriter {
     }
   }
 
-  private void addInBailiwickNameServerSet(DomainBase domain, Update update) {
+  private void addInBailiwickNameServerSet(Domain domain, Update update) {
     for (String hostName :
         intersection(domain.loadNameserverHostNames(), domain.getSubordinateHosts())) {
       Optional<HostResource> host = loadByForeignKey(HostResource.class, hostName, clock.nowUtc());
@@ -223,7 +222,7 @@ public class DnsUpdateWriter extends BaseDnsWriter {
     }
   }
 
-  private RRset makeNameServerSet(DomainBase domain) {
+  private RRset makeNameServerSet(Domain domain) {
     RRset nameServerSet = new RRset();
     for (String hostName : domain.loadNameserverHostNames()) {
       NSRecord record =

core/src/main/java/google/registry/env/alpha/backend/WEB-INF/appengine-web.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
-  <app-engine-apis>true</app-engine-apis>
+  <runtime>java8</runtime>
   <service>backend</service>
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4</instance-class>
   <basic-scaling>

core/src/main/java/google/registry/env/alpha/default/WEB-INF/appengine-web.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
-  <app-engine-apis>true</app-engine-apis>
+  <runtime>java8</runtime>
   <service>default</service>
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4</instance-class>
   <basic-scaling>

core/src/main/java/google/registry/env/alpha/pubapi/WEB-INF/appengine-web.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
-  <app-engine-apis>true</app-engine-apis>
+  <runtime>java8</runtime>
   <service>pubapi</service>
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4</instance-class>
   <basic-scaling>

core/src/main/java/google/registry/env/alpha/tools/WEB-INF/appengine-web.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
-  <app-engine-apis>true</app-engine-apis>
+  <runtime>java8</runtime>
   <service>tools</service>
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4</instance-class>
   <basic-scaling>

core/src/main/java/google/registry/env/common/default/WEB-INF/datastore-indexes.xml

@@ -6,22 +6,22 @@
     <property name="searchName" direction="asc"/>
   </datastore-index>
   <!-- For finding domain resources by registrar. -->
-  <datastore-index kind="DomainBase" ancestor="false" source="manual">
+  <datastore-index kind="Domain" ancestor="false" source="manual">
     <property name="currentSponsorClientId" direction="asc"/>
     <property name="deletionTime" direction="asc"/>
   </datastore-index>
   <!-- For finding domain resources by TLD. -->
-  <datastore-index kind="DomainBase" ancestor="false" source="manual">
+  <datastore-index kind="Domain" ancestor="false" source="manual">
     <property name="tld" direction="asc"/>
     <property name="deletionTime" direction="asc"/>
   </datastore-index>
   <!-- For finding domain resources by registrar. -->
-  <datastore-index kind="DomainBase" ancestor="false" source="manual">
+  <datastore-index kind="Domain" ancestor="false" source="manual">
     <property name="currentSponsorClientId" direction="asc"/>
     <property name="deletionTime" direction="asc"/>
   </datastore-index>
   <!-- For finding the most recently created domain resources. -->
-  <datastore-index kind="DomainBase" ancestor="false" source="manual">
+  <datastore-index kind="Domain" ancestor="false" source="manual">
     <property name="tld" direction="asc"/>
     <property name="creationTime" direction="desc"/>
   </datastore-index>
@@ -32,22 +32,22 @@
     <property name="fullyQualifiedHostName" direction="asc"/>
   </datastore-index>
   <!-- For determining the active domains linked to a given contact. -->
-  <datastore-index kind="DomainBase" ancestor="false" source="manual">
+  <datastore-index kind="Domain" ancestor="false" source="manual">
     <property name="allContacts.contact" direction="asc"/>
     <property name="deletionTime" direction="asc"/>
   </datastore-index>
   <!-- For determining the active domains linked to a given host. -->
-  <datastore-index kind="DomainBase" ancestor="false" source="manual">
+  <datastore-index kind="Domain" ancestor="false" source="manual">
     <property name="nsHosts" direction="asc"/>
     <property name="deletionTime" direction="asc"/>
   </datastore-index>
   <!-- For deleting expired not-previously-deleted domains. -->
-  <datastore-index kind="DomainBase" ancestor="false" source="manual">
+  <datastore-index kind="Domain" ancestor="false" source="manual">
     <property name="deletionTime" direction="asc"/>
     <property name="autorenewEndTime" direction="asc"/>
   </datastore-index>
   <!-- For RDAP searches by linked nameserver. -->
-  <datastore-index kind="DomainBase" ancestor="false" source="manual">
+  <datastore-index kind="Domain" ancestor="false" source="manual">
     <property name="nsHosts" direction="asc"/>
     <property name="deletionTime" direction="asc"/>
   </datastore-index>
@@ -74,16 +74,16 @@
     <property name="modificationTime" direction="asc"/>
   </datastore-index>
   <!-- For RDAP. -->
-  <datastore-index kind="DomainBase" ancestor="false" source="manual">
+  <datastore-index kind="Domain" ancestor="false" source="manual">
     <property name="currentSponsorClientId" direction="asc"/>
     <property name="fullyQualifiedDomainName" direction="asc"/>
   </datastore-index>
-  <datastore-index kind="DomainBase" ancestor="false" source="manual">
+  <datastore-index kind="Domain" ancestor="false" source="manual">
     <property name="currentSponsorClientId" direction="asc"/>
     <property name="tld" direction="asc"/>
     <property name="fullyQualifiedDomainName" direction="asc"/>
   </datastore-index>
-  <datastore-index kind="DomainBase" ancestor="false" source="manual">
+  <datastore-index kind="Domain" ancestor="false" source="manual">
     <property name="tld" direction="asc"/>
     <property name="fullyQualifiedDomainName" direction="asc"/>
   </datastore-index>

core/src/main/java/google/registry/env/crash/backend/WEB-INF/appengine-web.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
-  <app-engine-apis>true</app-engine-apis>
+  <runtime>java8</runtime>
   <service>backend</service>
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4</instance-class>
   <basic-scaling>

core/src/main/java/google/registry/env/crash/default/WEB-INF/appengine-web.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
-  <app-engine-apis>true</app-engine-apis>
+  <runtime>java8</runtime>
   <service>default</service>
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4_1G</instance-class>
   <basic-scaling>

core/src/main/java/google/registry/env/crash/pubapi/WEB-INF/appengine-web.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
-  <app-engine-apis>true</app-engine-apis>
+  <runtime>java8</runtime>
   <service>pubapi</service>
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4</instance-class>
   <basic-scaling>

core/src/main/java/google/registry/env/crash/tools/WEB-INF/appengine-web.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
-  <app-engine-apis>true</app-engine-apis>
+  <runtime>java8</runtime>
   <service>tools</service>
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4</instance-class>
   <basic-scaling>

core/src/main/java/google/registry/env/local/backend/WEB-INF/appengine-web.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
-  <app-engine-apis>true</app-engine-apis>
+  <runtime>java8</runtime>
   <service>backend</service>
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4</instance-class>
   <basic-scaling>

core/src/main/java/google/registry/env/local/default/WEB-INF/appengine-web.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
-  <app-engine-apis>true</app-engine-apis>
+  <runtime>java8</runtime>
   <service>default</service>
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4_1G</instance-class>
   <basic-scaling>

core/src/main/java/google/registry/env/local/pubapi/WEB-INF/appengine-web.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
-  <app-engine-apis>true</app-engine-apis>
+  <runtime>java8</runtime>
   <service>pubapi</service>
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4</instance-class>
   <basic-scaling>

core/src/main/java/google/registry/env/local/tools/WEB-INF/appengine-web.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
-  <app-engine-apis>true</app-engine-apis>
+  <runtime>java8</runtime>
   <service>tools</service>
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4</instance-class>
   <basic-scaling>

core/src/main/java/google/registry/env/production/backend/WEB-INF/appengine-web.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
-  <app-engine-apis>true</app-engine-apis>
+  <runtime>java8</runtime>
   <service>backend</service>
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4_1G</instance-class>
   <basic-scaling>

core/src/main/java/google/registry/env/production/default/WEB-INF/appengine-web.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
-  <app-engine-apis>true</app-engine-apis>
+  <runtime>java8</runtime>
   <service>default</service>
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4_1G</instance-class>
   <manual-scaling>

core/src/main/java/google/registry/env/production/pubapi/WEB-INF/appengine-web.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
-  <app-engine-apis>true</app-engine-apis>
+  <runtime>java8</runtime>
   <service>pubapi</service>
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4_1G</instance-class>
   <manual-scaling>

core/src/main/java/google/registry/env/production/tools/WEB-INF/appengine-web.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
-  <app-engine-apis>true</app-engine-apis>
+  <runtime>java8</runtime>
   <service>tools</service>
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4_1G</instance-class>
   <basic-scaling>

core/src/main/java/google/registry/env/qa/backend/WEB-INF/appengine-web.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
-  <app-engine-apis>true</app-engine-apis>
+  <runtime>java8</runtime>
   <service>backend</service>
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4</instance-class>
   <basic-scaling>

core/src/main/java/google/registry/env/qa/default/WEB-INF/appengine-web.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
-  <app-engine-apis>true</app-engine-apis>
+  <runtime>java8</runtime>
   <service>default</service>
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>F4_1G</instance-class>
   <automatic-scaling>

core/src/main/java/google/registry/env/qa/pubapi/WEB-INF/appengine-web.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
-  <app-engine-apis>true</app-engine-apis>
+  <runtime>java8</runtime>
   <service>pubapi</service>
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4</instance-class>
   <basic-scaling>

core/src/main/java/google/registry/env/qa/tools/WEB-INF/appengine-web.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
-  <app-engine-apis>true</app-engine-apis>
+  <runtime>java8</runtime>
   <service>tools</service>
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4</instance-class>
   <basic-scaling>

core/src/main/java/google/registry/env/sandbox/backend/WEB-INF/appengine-web.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
-  <app-engine-apis>true</app-engine-apis>
+  <runtime>java8</runtime>
   <service>backend</service>
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4</instance-class>
   <basic-scaling>

core/src/main/java/google/registry/env/sandbox/default/WEB-INF/appengine-web.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
-  <app-engine-apis>true</app-engine-apis>
+  <runtime>java8</runtime>
   <service>default</service>
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4_1G</instance-class>
   <manual-scaling>

core/src/main/java/google/registry/env/sandbox/pubapi/WEB-INF/appengine-web.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
-  <app-engine-apis>true</app-engine-apis>
+  <runtime>java8</runtime>
   <service>pubapi</service>
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4_1G</instance-class>
   <manual-scaling>

core/src/main/java/google/registry/env/sandbox/tools/WEB-INF/appengine-web.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
-  <runtime>java17</runtime>
-  <app-engine-apis>true</app-engine-apis>
+  <runtime>java8</runtime>
   <service>tools</service>
+  <threadsafe>true</threadsafe>
   <sessions-enabled>true</sessions-enabled>
   <instance-class>B4</instance-class>
   <basic-scaling>

core/src/main/java/google/registry/flows/CheckApiAction.java

@@ -44,7 +44,7 @@ import dagger.Module;
 import dagger.Provides;
 import google.registry.flows.domain.DomainFlowUtils.BadCommandForRegistryPhaseException;
 import google.registry.flows.domain.DomainFlowUtils.InvalidIdnDomainLabelException;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.index.ForeignKeyIndex;
 import google.registry.model.tld.Registry;
 import google.registry.model.tld.label.ReservationType;
@@ -156,8 +156,7 @@ public class CheckApiAction implements Runnable {
   }
 
   private boolean checkExists(String domainString, DateTime now) {
-    return !ForeignKeyIndex.loadCached(DomainBase.class, ImmutableList.of(domainString), now)
-        .isEmpty();
+    return !ForeignKeyIndex.loadCached(Domain.class, ImmutableList.of(domainString), now).isEmpty();
   }
 
   private Optional<String> checkReserved(InternetDomainName domainName) {

core/src/main/java/google/registry/flows/ResourceFlowUtils.java

@@ -39,8 +39,8 @@ import google.registry.model.EppResource;
 import google.registry.model.EppResource.ForeignKeyedEppResource;
 import google.registry.model.EppResource.ResourceWithTransferData;
 import google.registry.model.contact.ContactResource;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainBase;
-import google.registry.model.domain.DomainContent;
 import google.registry.model.domain.Period;
 import google.registry.model.domain.rgp.GracePeriodStatus;
 import google.registry.model.eppcommon.AuthInfo;
@@ -147,7 +147,7 @@ public final class ResourceFlowUtils {
   }
 
   /** Check that the given AuthInfo is either missing or else is valid for the given resource. */
-  public static void verifyOptionalAuthInfo(Optional<AuthInfo> authInfo, DomainBase domain)
+  public static void verifyOptionalAuthInfo(Optional<AuthInfo> authInfo, Domain domain)
       throws EppException {
     if (authInfo.isPresent()) {
       verifyAuthInfo(authInfo.get(), domain);
@@ -155,7 +155,7 @@ public final class ResourceFlowUtils {
   }
 
   /** Check that the given {@link AuthInfo} is valid for the given domain. */
-  public static void verifyAuthInfo(AuthInfo authInfo, DomainBase domain) throws EppException {
+  public static void verifyAuthInfo(AuthInfo authInfo, Domain domain) throws EppException {
     final String authRepoId = authInfo.getPw().getRepoId();
     String authPassword = authInfo.getPw().getValue();
     if (authRepoId == null) {
@@ -236,7 +236,7 @@ public final class ResourceFlowUtils {
    * @param domain is the domain already projected at approvalTime
    */
   public static DateTime computeExDateForApprovalTime(
-      DomainContent domain, DateTime approvalTime, Period period) {
+      DomainBase domain, DateTime approvalTime, Period period) {
     boolean inAutoRenew = domain.getGracePeriodStatuses().contains(GracePeriodStatus.AUTO_RENEW);
     // inAutoRenew is set to false if the period is zero because a zero-period transfer should not
     // subsume an autorenew.
@@ -246,7 +246,7 @@ public final class ResourceFlowUtils {
     if (period.getValue() == 0) {
       inAutoRenew = false;
     }
-    return DomainBase.extendRegistrationWithCap(
+    return Domain.extendRegistrationWithCap(
         approvalTime,
         domain.getRegistrationExpirationTime(),
         period.getValue() - (inAutoRenew ? 1 : 0));

core/src/main/java/google/registry/flows/custom/DomainCreateFlowCustomLogic.java

@@ -22,7 +22,7 @@ import google.registry.flows.FlowMetadata;
 import google.registry.flows.SessionMetadata;
 import google.registry.flows.domain.DomainCreateFlow;
 import google.registry.model.ImmutableObject;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.eppinput.EppInput;
 import google.registry.model.eppoutput.EppResponse.ResponseData;
 import google.registry.model.eppoutput.EppResponse.ResponseExtension;
@@ -125,10 +125,9 @@ public class DomainCreateFlowCustomLogic extends BaseFlowCustomLogic {
   public abstract static class BeforeSaveParameters extends ImmutableObject {
 
     /**
-     * The new {@link DomainBase} entity that is going to be persisted at the end of the
-     * transaction.
+     * The new {@link Domain} entity that is going to be persisted at the end of the transaction.
      */
-    public abstract DomainBase newDomain();
+    public abstract Domain newDomain();
 
     /**
      * The new {@link HistoryEntry} entity for the domain's creation that is going to be persisted
@@ -162,7 +161,7 @@ public class DomainCreateFlowCustomLogic extends BaseFlowCustomLogic {
     @AutoValue.Builder
     public abstract static class Builder {
 
-      public abstract Builder setNewDomain(DomainBase newDomain);
+      public abstract Builder setNewDomain(Domain newDomain);
 
       public abstract Builder setHistoryEntry(HistoryEntry historyEntry);
 

core/src/main/java/google/registry/flows/custom/DomainDeleteFlowCustomLogic.java

@@ -21,7 +21,7 @@ import google.registry.flows.FlowMetadata;
 import google.registry.flows.SessionMetadata;
 import google.registry.flows.domain.DomainDeleteFlow;
 import google.registry.model.ImmutableObject;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.eppinput.EppInput;
 import google.registry.model.eppoutput.EppResponse.ResponseExtension;
 import google.registry.model.eppoutput.Result;
@@ -83,7 +83,7 @@ public class DomainDeleteFlowCustomLogic extends BaseFlowCustomLogic {
   @AutoValue
   public abstract static class AfterValidationParameters extends ImmutableObject {
 
-    public abstract DomainBase existingDomain();
+    public abstract Domain existingDomain();
 
     public static Builder newBuilder() {
       return new AutoValue_DomainDeleteFlowCustomLogic_AfterValidationParameters.Builder();
@@ -93,7 +93,7 @@ public class DomainDeleteFlowCustomLogic extends BaseFlowCustomLogic {
     @AutoValue.Builder
     public abstract static class Builder {
 
-      public abstract Builder setExistingDomain(DomainBase existingDomain);
+      public abstract Builder setExistingDomain(Domain existingDomain);
 
       public abstract AfterValidationParameters build();
     }
@@ -109,9 +109,9 @@ public class DomainDeleteFlowCustomLogic extends BaseFlowCustomLogic {
   @AutoValue
   public abstract static class BeforeSaveParameters extends ImmutableObject {
 
-    public abstract DomainBase existingDomain();
+    public abstract Domain existingDomain();
 
-    public abstract DomainBase newDomain();
+    public abstract Domain newDomain();
 
     public abstract HistoryEntry historyEntry();
 
@@ -125,9 +125,9 @@ public class DomainDeleteFlowCustomLogic extends BaseFlowCustomLogic {
     @AutoValue.Builder
     public abstract static class Builder {
 
-      public abstract Builder setExistingDomain(DomainBase existingDomain);
+      public abstract Builder setExistingDomain(Domain existingDomain);
 
-      public abstract Builder setNewDomain(DomainBase newDomain);
+      public abstract Builder setNewDomain(Domain newDomain);
 
       public abstract Builder setHistoryEntry(HistoryEntry historyEntry);
 

core/src/main/java/google/registry/flows/custom/DomainInfoFlowCustomLogic.java

@@ -21,7 +21,7 @@ import google.registry.flows.FlowMetadata;
 import google.registry.flows.SessionMetadata;
 import google.registry.flows.domain.DomainInfoFlow;
 import google.registry.model.ImmutableObject;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainInfoData;
 import google.registry.model.eppinput.EppInput;
 import google.registry.model.eppoutput.EppResponse.ResponseExtension;
@@ -53,8 +53,8 @@ public class DomainInfoFlowCustomLogic extends BaseFlowCustomLogic {
   /**
    * A hook that runs before the response is returned.
    *
-   * <p>This takes the {@link DomainBase} and {@link ResponseExtension}s as input and returns
-   * them, potentially with modifications.
+   * <p>This takes the {@link Domain} and {@link ResponseExtension}s as input and returns them,
+   * potentially with modifications.
    */
   @SuppressWarnings("unused")
   public BeforeResponseReturnData beforeResponse(BeforeResponseParameters parameters)
@@ -69,7 +69,7 @@ public class DomainInfoFlowCustomLogic extends BaseFlowCustomLogic {
   @AutoValue
   public abstract static class AfterValidationParameters extends ImmutableObject {
 
-    public abstract DomainBase domain();
+    public abstract Domain domain();
 
     public static Builder newBuilder() {
       return new AutoValue_DomainInfoFlowCustomLogic_AfterValidationParameters.Builder();
@@ -79,7 +79,7 @@ public class DomainInfoFlowCustomLogic extends BaseFlowCustomLogic {
     @AutoValue.Builder
     public abstract static class Builder {
 
-      public abstract Builder setDomain(DomainBase domain);
+      public abstract Builder setDomain(Domain domain);
 
       public abstract AfterValidationParameters build();
     }
@@ -89,7 +89,7 @@ public class DomainInfoFlowCustomLogic extends BaseFlowCustomLogic {
   @AutoValue
   public abstract static class BeforeResponseParameters extends ImmutableObject {
 
-    public abstract DomainBase domain();
+    public abstract Domain domain();
 
     public abstract DomainInfoData resData();
 
@@ -103,7 +103,7 @@ public class DomainInfoFlowCustomLogic extends BaseFlowCustomLogic {
     @AutoValue.Builder
     public abstract static class Builder {
 
-      public abstract Builder setDomain(DomainBase domain);
+      public abstract Builder setDomain(Domain domain);
 
       public abstract Builder setResData(DomainInfoData resData);
 

core/src/main/java/google/registry/flows/custom/DomainRenewFlowCustomLogic.java

@@ -21,7 +21,7 @@ import google.registry.flows.FlowMetadata;
 import google.registry.flows.SessionMetadata;
 import google.registry.flows.domain.DomainRenewFlow;
 import google.registry.model.ImmutableObject;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.eppinput.EppInput;
 import google.registry.model.eppoutput.EppResponse.ResponseData;
 import google.registry.model.eppoutput.EppResponse.ResponseExtension;
@@ -68,8 +68,8 @@ public class DomainRenewFlowCustomLogic extends BaseFlowCustomLogic {
   /**
    * A hook that runs before the response is returned.
    *
-   * <p>This takes the {@link DomainBase} and {@link ResponseExtension}s as input and returns
-   * them, potentially with modifications.
+   * <p>This takes the {@link Domain} and {@link ResponseExtension}s as input and returns them,
+   * potentially with modifications.
    */
   @SuppressWarnings("unused")
   public BeforeResponseReturnData beforeResponse(BeforeResponseParameters parameters)
@@ -84,7 +84,7 @@ public class DomainRenewFlowCustomLogic extends BaseFlowCustomLogic {
   @AutoValue
   public abstract static class AfterValidationParameters extends ImmutableObject {
 
-    public abstract DomainBase existingDomain();
+    public abstract Domain existingDomain();
 
     public abstract int years();
 
@@ -98,7 +98,7 @@ public class DomainRenewFlowCustomLogic extends BaseFlowCustomLogic {
     @AutoValue.Builder
     public abstract static class Builder {
 
-      public abstract Builder setExistingDomain(DomainBase existingDomain);
+      public abstract Builder setExistingDomain(Domain existingDomain);
 
       public abstract Builder setYears(int years);
 
@@ -118,9 +118,9 @@ public class DomainRenewFlowCustomLogic extends BaseFlowCustomLogic {
   @AutoValue
   public abstract static class BeforeSaveParameters extends ImmutableObject {
 
-    public abstract DomainBase existingDomain();
+    public abstract Domain existingDomain();
 
-    public abstract DomainBase newDomain();
+    public abstract Domain newDomain();
 
     public abstract HistoryEntry historyEntry();
 
@@ -138,9 +138,9 @@ public class DomainRenewFlowCustomLogic extends BaseFlowCustomLogic {
     @AutoValue.Builder
     public abstract static class Builder {
 
-      public abstract Builder setExistingDomain(DomainBase existingDomain);
+      public abstract Builder setExistingDomain(Domain existingDomain);
 
-      public abstract Builder setNewDomain(DomainBase newDomain);
+      public abstract Builder setNewDomain(Domain newDomain);
 
       public abstract Builder setHistoryEntry(HistoryEntry historyEntry);
 
@@ -158,7 +158,7 @@ public class DomainRenewFlowCustomLogic extends BaseFlowCustomLogic {
   @AutoValue
   public abstract static class BeforeResponseParameters extends ImmutableObject {
 
-    public abstract DomainBase domain();
+    public abstract Domain domain();
 
     public abstract ResponseData resData();
 
@@ -172,7 +172,7 @@ public class DomainRenewFlowCustomLogic extends BaseFlowCustomLogic {
     @AutoValue.Builder
     public abstract static class Builder {
 
-      public abstract BeforeResponseParameters.Builder setDomain(DomainBase domain);
+      public abstract BeforeResponseParameters.Builder setDomain(Domain domain);
 
       public abstract BeforeResponseParameters.Builder setResData(ResponseData resData);
 

core/src/main/java/google/registry/flows/custom/DomainUpdateFlowCustomLogic.java

@@ -20,7 +20,7 @@ import google.registry.flows.FlowMetadata;
 import google.registry.flows.SessionMetadata;
 import google.registry.flows.domain.DomainUpdateFlow;
 import google.registry.model.ImmutableObject;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.eppinput.EppInput;
 import google.registry.model.reporting.HistoryEntry;
 
@@ -65,7 +65,7 @@ public class DomainUpdateFlowCustomLogic extends BaseFlowCustomLogic {
   @AutoValue
   public abstract static class AfterValidationParameters extends ImmutableObject {
 
-    public abstract DomainBase existingDomain();
+    public abstract Domain existingDomain();
 
     public static Builder newBuilder() {
       return new AutoValue_DomainUpdateFlowCustomLogic_AfterValidationParameters.Builder();
@@ -75,7 +75,7 @@ public class DomainUpdateFlowCustomLogic extends BaseFlowCustomLogic {
     @AutoValue.Builder
     public abstract static class Builder {
 
-      public abstract Builder setExistingDomain(DomainBase existingDomain);
+      public abstract Builder setExistingDomain(Domain existingDomain);
 
       public abstract AfterValidationParameters build();
     }
@@ -91,9 +91,9 @@ public class DomainUpdateFlowCustomLogic extends BaseFlowCustomLogic {
   @AutoValue
   public abstract static class BeforeSaveParameters extends ImmutableObject {
 
-    public abstract DomainBase existingDomain();
+    public abstract Domain existingDomain();
 
-    public abstract DomainBase newDomain();
+    public abstract Domain newDomain();
 
     public abstract HistoryEntry historyEntry();
 
@@ -107,9 +107,9 @@ public class DomainUpdateFlowCustomLogic extends BaseFlowCustomLogic {
     @AutoValue.Builder
     public abstract static class Builder {
 
-      public abstract Builder setExistingDomain(DomainBase existingDomain);
+      public abstract Builder setExistingDomain(Domain existingDomain);
 
-      public abstract Builder setNewDomain(DomainBase newDomain);
+      public abstract Builder setNewDomain(Domain newDomain);
 
       public abstract Builder setHistoryEntry(HistoryEntry historyEntry);
 

core/src/main/java/google/registry/flows/domain/DomainCheckFlow.java

@@ -54,7 +54,7 @@ import google.registry.flows.domain.token.AllocationTokenDomainCheckResults;
 import google.registry.flows.domain.token.AllocationTokenFlowUtils;
 import google.registry.model.EppResource;
 import google.registry.model.billing.BillingEvent;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainCommand.Check;
 import google.registry.model.domain.fee.FeeCheckCommandExtension;
 import google.registry.model.domain.fee.FeeCheckCommandExtensionItem;
@@ -169,8 +169,8 @@ public final class DomainCheckFlow implements Flow {
             // TODO: Use as of date from fee extension v0.12 instead of now, if specified.
             .setAsOfDate(now)
             .build());
-    ImmutableMap<String, ForeignKeyIndex<DomainBase>> existingDomains =
-        ForeignKeyIndex.load(DomainBase.class, domainNames, now);
+    ImmutableMap<String, ForeignKeyIndex<Domain>> existingDomains =
+        ForeignKeyIndex.load(Domain.class, domainNames, now);
     Optional<AllocationTokenExtension> allocationTokenExtension =
         eppInput.getSingleExtension(AllocationTokenExtension.class);
     Optional<AllocationTokenDomainCheckResults> tokenDomainCheckResults =
@@ -227,7 +227,7 @@ public final class DomainCheckFlow implements Flow {
 
   private Optional<String> getMessageForCheck(
       InternetDomainName domainName,
-      ImmutableMap<String, ForeignKeyIndex<DomainBase>> existingDomains,
+      ImmutableMap<String, ForeignKeyIndex<Domain>> existingDomains,
       ImmutableMap<InternetDomainName, String> tokenCheckResults,
       ImmutableMap<String, TldState> tldStates,
       Optional<AllocationToken> allocationToken) {
@@ -251,7 +251,7 @@ public final class DomainCheckFlow implements Flow {
   /** Handle the fee check extension. */
   private ImmutableList<? extends ResponseExtension> getResponseExtensions(
       ImmutableMap<String, InternetDomainName> domainNames,
-      ImmutableMap<String, ForeignKeyIndex<DomainBase>> existingDomains,
+      ImmutableMap<String, ForeignKeyIndex<Domain>> existingDomains,
       ImmutableSet<String> availableDomains,
       DateTime now,
       Optional<AllocationToken> allocationToken)
@@ -264,7 +264,7 @@ public final class DomainCheckFlow implements Flow {
     FeeCheckCommandExtension<?, ?> feeCheck = feeCheckOpt.get();
     ImmutableList.Builder<FeeCheckResponseExtensionItem> responseItems =
         new ImmutableList.Builder<>();
-    ImmutableMap<String, DomainBase> domainObjs =
+    ImmutableMap<String, Domain> domainObjs =
         loadDomainsForRestoreChecks(feeCheck, domainNames, existingDomains);
     ImmutableMap<String, BillingEvent.Recurring> recurrences =
         loadRecurrencesForDomains(domainObjs);
@@ -272,12 +272,12 @@ public final class DomainCheckFlow implements Flow {
     for (FeeCheckCommandExtensionItem feeCheckItem : feeCheck.getItems()) {
       for (String domainName : getDomainNamesToCheckForFee(feeCheckItem, domainNames.keySet())) {
         FeeCheckResponseExtensionItem.Builder<?> builder = feeCheckItem.createResponseBuilder();
-        Optional<DomainBase> domainBase = Optional.ofNullable(domainObjs.get(domainName));
+        Optional<Domain> domain = Optional.ofNullable(domainObjs.get(domainName));
         handleFeeRequest(
             feeCheckItem,
             builder,
             domainNames.get(domainName),
-            domainBase,
+            domain,
             feeCheck.getCurrency(),
             now,
             pricingLogic,
@@ -301,10 +301,10 @@ public final class DomainCheckFlow implements Flow {
    * nicer in Cloud SQL when we can SELECT just the fields we want rather than having to load the
    * entire entity.
    */
-  private ImmutableMap<String, DomainBase> loadDomainsForRestoreChecks(
+  private ImmutableMap<String, Domain> loadDomainsForRestoreChecks(
       FeeCheckCommandExtension<?, ?> feeCheck,
       ImmutableMap<String, InternetDomainName> domainNames,
-      ImmutableMap<String, ForeignKeyIndex<DomainBase>> existingDomains) {
+      ImmutableMap<String, ForeignKeyIndex<Domain>> existingDomains) {
     ImmutableList<String> restoreCheckDomains;
     if (feeCheck instanceof FeeCheckCommandExtensionV06) {
       // The V06 fee extension supports specifying the command fees to check on a per-domain basis.
@@ -326,25 +326,25 @@ public final class DomainCheckFlow implements Flow {
     }
 
     // Filter down to just domains we know exist and then use the EppResource cache to load them.
-    ImmutableMap<String, VKey<DomainBase>> existingDomainsToLoad =
+    ImmutableMap<String, VKey<Domain>> existingDomainsToLoad =
         restoreCheckDomains.stream()
             .filter(existingDomains::containsKey)
             .collect(toImmutableMap(d -> d, d -> existingDomains.get(d).getResourceKey()));
     ImmutableMap<VKey<? extends EppResource>, EppResource> loadedDomains =
         EppResource.loadCached(ImmutableList.copyOf(existingDomainsToLoad.values()));
     return ImmutableMap.copyOf(
-        Maps.transformEntries(existingDomainsToLoad, (k, v) -> (DomainBase) loadedDomains.get(v)));
+        Maps.transformEntries(existingDomainsToLoad, (k, v) -> (Domain) loadedDomains.get(v)));
   }
 
   private ImmutableMap<String, BillingEvent.Recurring> loadRecurrencesForDomains(
-      ImmutableMap<String, DomainBase> domainObjs) {
+      ImmutableMap<String, Domain> domainObjs) {
     return tm().transact(
             () -> {
               ImmutableMap<VKey<? extends BillingEvent.Recurring>, BillingEvent.Recurring>
                   recurrences =
                       tm().loadByKeys(
                               domainObjs.values().stream()
-                                  .map(DomainBase::getAutorenewBillingEvent)
+                                  .map(Domain::getAutorenewBillingEvent)
                                   .collect(toImmutableSet()));
               return ImmutableMap.copyOf(
                   Maps.transformValues(

core/src/main/java/google/registry/flows/domain/DomainCreateFlow.java

@@ -83,7 +83,7 @@ import google.registry.model.billing.BillingEvent.Flag;
 import google.registry.model.billing.BillingEvent.Reason;
 import google.registry.model.billing.BillingEvent.Recurring;
 import google.registry.model.billing.BillingEvent.RenewalPriceBehavior;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainCommand;
 import google.registry.model.domain.DomainCommand.Create;
 import google.registry.model.domain.DomainHistory;
@@ -247,7 +247,7 @@ public final class DomainCreateFlow implements TransactionalFlow {
     verifyUnitIsYears(period);
     int years = period.getValue();
     validateRegistrationPeriod(years);
-    verifyResourceDoesNotExist(DomainBase.class, targetId, now, registrarId);
+    verifyResourceDoesNotExist(Domain.class, targetId, now, registrarId);
     // Validate that this is actually a legal domain name on a TLD that the registrar has access to.
     InternetDomainName domainName = validateDomainName(command.getFullyQualifiedDomainName());
     String domainLabel = domainName.parts().get(0);
@@ -333,9 +333,9 @@ public final class DomainCreateFlow implements TransactionalFlow {
         validateSecDnsExtension(eppInput.getSingleExtension(SecDnsCreateExtension.class));
     DateTime registrationExpirationTime = leapSafeAddYears(now, years);
     String repoId = createDomainRepoId(allocateId(), registry.getTldStr());
-    Key<DomainHistory> domainHistoryKey =
-        Key.create(Key.create(DomainBase.class, repoId), DomainHistory.class, allocateId());
-    historyBuilder.setId(domainHistoryKey.getId());
+    long historyRevisionId = allocateId();
+    DomainHistoryId domainHistoryId = new DomainHistoryId(repoId, historyRevisionId);
+    historyBuilder.setId(historyRevisionId);
     // Bill for the create.
     BillingEvent.OneTime createBillingEvent =
         createOneTimeBillingEvent(
@@ -345,17 +345,17 @@ public final class DomainCreateFlow implements TransactionalFlow {
             isReserved(domainName, isSunriseCreate),
             years,
             feesAndCredits,
-            domainHistoryKey,
+            domainHistoryId,
             allocationToken,
             now);
     // Create a new autorenew billing event and poll message starting at the expiration time.
     BillingEvent.Recurring autorenewBillingEvent =
         createAutorenewBillingEvent(
-            domainHistoryKey,
+            domainHistoryId,
             registrationExpirationTime,
             getRenewalPriceInfo(isAnchorTenant, allocationToken, feesAndCredits));
     PollMessage.Autorenew autorenewPollMessage =
-        createAutorenewPollMessage(domainHistoryKey, registrationExpirationTime);
+        createAutorenewPollMessage(domainHistoryId, registrationExpirationTime);
     ImmutableSet.Builder<ImmutableObject> entitiesToSave = new ImmutableSet.Builder<>();
     entitiesToSave.add(createBillingEvent, autorenewBillingEvent, autorenewPollMessage);
     // Bill for EAP cost, if any.
@@ -368,8 +368,8 @@ public final class DomainCreateFlow implements TransactionalFlow {
         reservationTypes.contains(NAME_COLLISION)
             ? ImmutableSet.of(SERVER_HOLD)
             : ImmutableSet.of();
-    DomainBase domain =
-        new DomainBase.Builder()
+    Domain domain =
+        new Domain.Builder()
             .setCreationRegistrarId(registrarId)
             .setPersistedCurrentSponsorRegistrarId(registrarId)
             .setRepoId(repoId)
@@ -530,7 +530,7 @@ public final class DomainCreateFlow implements TransactionalFlow {
   }
 
   private DomainHistory buildDomainHistory(
-      DomainBase domain, Registry registry, DateTime now, Period period, Duration addGracePeriod) {
+      Domain domain, Registry registry, DateTime now, Period period, Duration addGracePeriod) {
     // We ignore prober transactions
     if (registry.getTldType() == TldType.REAL) {
       historyBuilder
@@ -552,7 +552,7 @@ public final class DomainCreateFlow implements TransactionalFlow {
       boolean isReserved,
       int years,
       FeesAndCredits feesAndCredits,
-      Key<DomainHistory> domainHistoryKey,
+      DomainHistoryId domainHistoryId,
       Optional<AllocationToken> allocationToken,
       DateTime now) {
     ImmutableSet.Builder<Flag> flagsBuilder = new ImmutableSet.Builder<>();
@@ -581,12 +581,12 @@ public final class DomainCreateFlow implements TransactionalFlow {
                     ? registry.getAnchorTenantAddGracePeriodLength()
                     : registry.getAddGracePeriodLength()))
         .setFlags(flagsBuilder.build())
-        .setParent(domainHistoryKey)
+        .setDomainHistoryId(domainHistoryId)
         .build();
   }
 
   private Recurring createAutorenewBillingEvent(
-      Key<DomainHistory> domainHistoryKey,
+      DomainHistoryId domainHistoryId,
       DateTime registrationExpirationTime,
       RenewalPriceInfo renewalpriceInfo) {
     return new BillingEvent.Recurring.Builder()
@@ -596,21 +596,20 @@ public final class DomainCreateFlow implements TransactionalFlow {
         .setRegistrarId(registrarId)
         .setEventTime(registrationExpirationTime)
         .setRecurrenceEndTime(END_OF_TIME)
-        .setParent(domainHistoryKey)
+        .setDomainHistoryId(domainHistoryId)
         .setRenewalPriceBehavior(renewalpriceInfo.renewalPriceBehavior())
         .setRenewalPrice(renewalpriceInfo.renewalPrice())
         .build();
   }
 
   private Autorenew createAutorenewPollMessage(
-      Key<DomainHistory> domainHistoryKey, DateTime registrationExpirationTime) {
+      DomainHistoryId domainHistoryId, DateTime registrationExpirationTime) {
     return new PollMessage.Autorenew.Builder()
         .setTargetId(targetId)
         .setRegistrarId(registrarId)
         .setEventTime(registrationExpirationTime)
         .setMsg("Domain was auto-renewed.")
-        .setDomainHistoryId(
-            new DomainHistoryId(domainHistoryKey.getParent().getName(), domainHistoryKey.getId()))
+        .setDomainHistoryId(domainHistoryId)
         .build();
   }
 
@@ -625,7 +624,7 @@ public final class DomainCreateFlow implements TransactionalFlow {
         .setEventTime(createBillingEvent.getEventTime())
         .setBillingTime(createBillingEvent.getBillingTime())
         .setFlags(createBillingEvent.getFlags())
-        .setParent(createBillingEvent.getParentKey())
+        .setDomainHistoryId(createBillingEvent.getDomainHistoryId())
         .build();
   }
 
@@ -646,13 +645,12 @@ public final class DomainCreateFlow implements TransactionalFlow {
         .build();
   }
 
-  private void enqueueTasks(
-      DomainBase newDomain, boolean hasSignedMarks, boolean hasClaimsNotice) {
+  private void enqueueTasks(Domain newDomain, boolean hasSignedMarks, boolean hasClaimsNotice) {
     if (newDomain.shouldPublishToDns()) {
       dnsQueue.addDomainRefreshTask(newDomain.getDomainName());
     }
     if (hasClaimsNotice || hasSignedMarks) {
-      LordnTaskUtils.enqueueDomainBaseTask(newDomain);
+      LordnTaskUtils.enqueueDomainTask(newDomain);
     }
   }
 

core/src/main/java/google/registry/flows/domain/DomainDeleteFlow.java

@@ -64,7 +64,7 @@ import google.registry.flows.custom.DomainDeleteFlowCustomLogic.BeforeSaveParame
 import google.registry.flows.custom.EntityChanges;
 import google.registry.model.ImmutableObject;
 import google.registry.model.billing.BillingEvent;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainHistory;
 import google.registry.model.domain.DomainHistory.DomainHistoryId;
 import google.registry.model.domain.GracePeriod;
@@ -146,13 +146,13 @@ public final class DomainDeleteFlow implements TransactionalFlow {
     extensionManager.validate();
     DateTime now = tm().getTransactionTime();
     // Loads the target resource if it exists
-    DomainBase existingDomain = loadAndVerifyExistence(DomainBase.class, targetId, now);
+    Domain existingDomain = loadAndVerifyExistence(Domain.class, targetId, now);
     Registry registry = Registry.get(existingDomain.getTld());
     verifyDeleteAllowed(existingDomain, registry, now);
     flowCustomLogic.afterValidation(
         AfterValidationParameters.newBuilder().setExistingDomain(existingDomain).build());
     ImmutableSet.Builder<ImmutableObject> entitiesToSave = new ImmutableSet.Builder<>();
-    DomainBase.Builder builder;
+    Domain.Builder builder;
     if (existingDomain.getStatusValues().contains(StatusValue.PENDING_TRANSFER)) {
       builder =
           denyPendingTransfer(existingDomain, TransferStatus.SERVER_CANCELLED, now, registrarId)
@@ -233,7 +233,12 @@ public final class DomainDeleteFlow implements TransactionalFlow {
       // No cancellation is written if the grace period was not for a billable event.
       if (gracePeriod.hasBillingEvent()) {
         entitiesToSave.add(
-            BillingEvent.Cancellation.forGracePeriod(gracePeriod, now, domainHistoryKey, targetId));
+            BillingEvent.Cancellation.forGracePeriod(
+                gracePeriod,
+                now,
+                new DomainHistoryId(
+                    domainHistoryKey.getParent().getName(), domainHistoryKey.getId()),
+                targetId));
         if (gracePeriod.getOneTimeBillingEvent() != null) {
           // Take the amount of amount of registration time being refunded off the expiration time.
           // This can be either add grace periods or renew grace periods.
@@ -248,7 +253,7 @@ public final class DomainDeleteFlow implements TransactionalFlow {
     }
     builder.setRegistrationExpirationTime(newExpirationTime);
 
-    DomainBase newDomain = builder.build();
+    Domain newDomain = builder.build();
     DomainHistory domainHistory =
         buildDomainHistory(newDomain, registry, now, durationUntilDelete, inAddGracePeriod);
     updateForeignKeyIndexDeletionTime(newDomain);
@@ -289,7 +294,7 @@ public final class DomainDeleteFlow implements TransactionalFlow {
         .build();
   }
 
-  private void verifyDeleteAllowed(DomainBase existingDomain, Registry registry, DateTime now)
+  private void verifyDeleteAllowed(Domain existingDomain, Registry registry, DateTime now)
       throws EppException {
     verifyNoDisallowedStatuses(existingDomain, DISALLOWED_STATUSES);
     verifyOptionalAuthInfo(authInfo, existingDomain);
@@ -304,7 +309,7 @@ public final class DomainDeleteFlow implements TransactionalFlow {
   }
 
   private DomainHistory buildDomainHistory(
-      DomainBase domain,
+      Domain domain,
       Registry registry,
       DateTime now,
       Duration durationUntilDelete,
@@ -337,7 +342,7 @@ public final class DomainDeleteFlow implements TransactionalFlow {
   }
 
   private PollMessage.OneTime createDeletePollMessage(
-      DomainBase existingDomain, Key<DomainHistory> domainHistoryKey, DateTime deletionTime) {
+      Domain existingDomain, Key<DomainHistory> domainHistoryKey, DateTime deletionTime) {
     Optional<MetadataExtension> metadataExtension =
         eppInput.getSingleExtension(MetadataExtension.class);
     boolean hasMetadataMessage =
@@ -362,7 +367,7 @@ public final class DomainDeleteFlow implements TransactionalFlow {
   }
 
   private PollMessage.OneTime createImmediateDeletePollMessage(
-      DomainBase existingDomain,
+      Domain existingDomain,
       Key<DomainHistory> domainHistoryKey,
       DateTime now,
       DateTime deletionTime) {
@@ -384,7 +389,7 @@ public final class DomainDeleteFlow implements TransactionalFlow {
 
   @Nullable
   private ImmutableList<FeeTransformResponseExtension> getResponseExtensions(
-      BillingEvent.Recurring recurringBillingEvent, DomainBase existingDomain, DateTime now) {
+      BillingEvent.Recurring recurringBillingEvent, Domain existingDomain, DateTime now) {
     FeeTransformResponseExtension.Builder feeResponseBuilder = getDeleteResponseBuilder();
     if (feeResponseBuilder == null) {
       return ImmutableList.of();

core/src/main/java/google/registry/flows/domain/DomainFlowUtils.java

@@ -25,7 +25,7 @@ import static com.google.common.collect.Iterables.any;
 import static com.google.common.collect.Sets.difference;
 import static com.google.common.collect.Sets.intersection;
 import static com.google.common.collect.Sets.union;
-import static google.registry.model.domain.DomainBase.MAX_REGISTRATION_YEARS;
+import static google.registry.model.domain.Domain.MAX_REGISTRATION_YEARS;
 import static google.registry.model.tld.Registries.findTldForName;
 import static google.registry.model.tld.Registries.getTlds;
 import static google.registry.model.tld.Registry.TldState.GENERAL_AVAILABILITY;
@@ -82,7 +82,7 @@ import google.registry.model.billing.BillingEvent.Recurring;
 import google.registry.model.contact.ContactResource;
 import google.registry.model.domain.DesignatedContact;
 import google.registry.model.domain.DesignatedContact.Type;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainCommand.Create;
 import google.registry.model.domain.DomainCommand.CreateOrUpdate;
 import google.registry.model.domain.DomainCommand.InvalidReferencesException;
@@ -553,7 +553,7 @@ public class DomainFlowUtils {
    * Fills in a builder with the data needed for an autorenew billing event for this domain. This
    * does not copy over the id of the current autorenew billing event.
    */
-  public static BillingEvent.Recurring.Builder newAutorenewBillingEvent(DomainBase domain) {
+  public static BillingEvent.Recurring.Builder newAutorenewBillingEvent(Domain domain) {
     return new BillingEvent.Recurring.Builder()
         .setReason(Reason.RENEW)
         .setFlags(ImmutableSet.of(Flag.AUTO_RENEW))
@@ -566,7 +566,7 @@ public class DomainFlowUtils {
    * Fills in a builder with the data needed for an autorenew poll message for this domain. This
    * does not copy over the id of the current autorenew poll message.
    */
-  public static PollMessage.Autorenew.Builder newAutorenewPollMessage(DomainBase domain) {
+  public static PollMessage.Autorenew.Builder newAutorenewPollMessage(Domain domain) {
     return new PollMessage.Autorenew.Builder()
         .setTargetId(domain.getDomainName())
         .setRegistrarId(domain.getCurrentSponsorRegistrarId())
@@ -583,7 +583,7 @@ public class DomainFlowUtils {
    *
    * <p>Returns the new autorenew recurring billing event.
    */
-  public static Recurring updateAutorenewRecurrenceEndTime(DomainBase domain, DateTime newEndTime) {
+  public static Recurring updateAutorenewRecurrenceEndTime(Domain domain, DateTime newEndTime) {
     Optional<PollMessage.Autorenew> autorenewPollMessage =
         tm().loadByKeyIfPresent(domain.getAutorenewPollMessage());
 
@@ -628,7 +628,7 @@ public class DomainFlowUtils {
       FeeQueryCommandExtensionItem feeRequest,
       FeeQueryResponseExtensionItem.Builder<?, ?> builder,
       InternetDomainName domainName,
-      Optional<DomainBase> domain,
+      Optional<Domain> domain,
       @Nullable CurrencyUnit topLevelCurrency,
       DateTime currentDate,
       DomainPricingLogic pricingLogic,
@@ -878,7 +878,7 @@ public class DomainFlowUtils {
 
   /**
    * Check whether a new expiration time (via a renew) does not extend beyond a maximum number of
-   * years (e.g. {@link DomainBase#MAX_REGISTRATION_YEARS}) from "now".
+   * years (e.g. {@link Domain#MAX_REGISTRATION_YEARS}) from "now".
    *
    * @throws ExceedsMaxRegistrationYearsException if the new registration period is too long
    */
@@ -891,7 +891,7 @@ public class DomainFlowUtils {
 
   /**
    * Check that a new registration period (via a create) does not extend beyond a maximum number of
-   * years (e.g. {@link DomainBase#MAX_REGISTRATION_YEARS}).
+   * years (e.g. {@link Domain#MAX_REGISTRATION_YEARS}).
    *
    * @throws ExceedsMaxRegistrationYearsException if the new registration period is too long
    */
@@ -947,7 +947,7 @@ public class DomainFlowUtils {
   }
 
   /** If a domain "clientUpdateProhibited" set, updates must clear it or fail. */
-  static void verifyClientUpdateNotProhibited(Update command, DomainBase existingResource)
+  static void verifyClientUpdateNotProhibited(Update command, Domain existingResource)
       throws ResourceHasClientUpdateProhibitedException {
     if (existingResource.getStatusValues().contains(StatusValue.CLIENT_UPDATE_PROHIBITED)
         && !command
@@ -1120,13 +1120,13 @@ public class DomainFlowUtils {
    * the most recent HistoryEntry that fits the above criteria, with negated reportAmounts.
    */
   static ImmutableSet<DomainTransactionRecord> createCancelingRecords(
-      DomainBase domainBase,
+      Domain domain,
       final DateTime now,
       Duration maxSearchPeriod,
       final ImmutableSet<TransactionReportField> cancelableFields) {
 
     List<? extends HistoryEntry> recentHistoryEntries =
-        findRecentHistoryEntries(domainBase, now, maxSearchPeriod);
+        findRecentHistoryEntries(domain, now, maxSearchPeriod);
     Optional<? extends HistoryEntry> entryToCancel =
         Streams.findLast(
             recentHistoryEntries.stream()
@@ -1165,14 +1165,14 @@ public class DomainFlowUtils {
   }
 
   private static List<? extends HistoryEntry> findRecentHistoryEntries(
-      DomainBase domainBase, DateTime now, Duration maxSearchPeriod) {
+      Domain domain, DateTime now, Duration maxSearchPeriod) {
     return jpaTm()
         .query(
             "FROM DomainHistory WHERE modificationTime >= :beginning AND domainRepoId = "
                 + ":repoId ORDER BY modificationTime ASC",
             DomainHistory.class)
         .setParameter("beginning", now.minus(maxSearchPeriod))
-        .setParameter("repoId", domainBase.getRepoId())
+        .setParameter("repoId", domain.getRepoId())
         .getResultList();
   }
 

core/src/main/java/google/registry/flows/domain/DomainInfoFlow.java

@@ -36,7 +36,7 @@ import google.registry.flows.custom.DomainInfoFlowCustomLogic;
 import google.registry.flows.custom.DomainInfoFlowCustomLogic.AfterValidationParameters;
 import google.registry.flows.custom.DomainInfoFlowCustomLogic.BeforeResponseParameters;
 import google.registry.flows.custom.DomainInfoFlowCustomLogic.BeforeResponseReturnData;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainCommand.Info;
 import google.registry.model.domain.DomainCommand.Info.HostsRequest;
 import google.registry.model.domain.DomainInfoData;
@@ -96,8 +96,8 @@ public final class DomainInfoFlow implements Flow {
     validateRegistrarIsLoggedIn(registrarId);
     extensionManager.validate();
     DateTime now = clock.nowUtc();
-    DomainBase domain = verifyExistence(
-        DomainBase.class, targetId, loadByForeignKey(DomainBase.class, targetId, now));
+    Domain domain =
+        verifyExistence(Domain.class, targetId, loadByForeignKey(Domain.class, targetId, now));
     verifyOptionalAuthInfo(authInfo, domain);
     flowCustomLogic.afterValidation(
         AfterValidationParameters.newBuilder().setDomain(domain).build());
@@ -142,8 +142,8 @@ public final class DomainInfoFlow implements Flow {
         .build();
   }
 
-  private ImmutableList<ResponseExtension> getDomainResponseExtensions(
-      DomainBase domain, DateTime now) throws EppException {
+  private ImmutableList<ResponseExtension> getDomainResponseExtensions(Domain domain, DateTime now)
+      throws EppException {
     ImmutableList.Builder<ResponseExtension> extensions = new ImmutableList.Builder<>();
     addSecDnsExtensionIfPresent(extensions, domain.getDsData());
     ImmutableSet<GracePeriodStatus> gracePeriodStatuses = domain.getGracePeriodStatuses();

core/src/main/java/google/registry/flows/domain/DomainRenewFlow.java

@@ -57,7 +57,7 @@ import google.registry.model.billing.BillingEvent;
 import google.registry.model.billing.BillingEvent.OneTime;
 import google.registry.model.billing.BillingEvent.Reason;
 import google.registry.model.billing.BillingEvent.Recurring;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainCommand.Renew;
 import google.registry.model.domain.DomainHistory;
 import google.registry.model.domain.DomainHistory.DomainHistoryId;
@@ -166,7 +166,7 @@ public final class DomainRenewFlow implements TransactionalFlow {
     DateTime now = tm().getTransactionTime();
     Renew command = (Renew) resourceCommand;
     // Loads the target resource if it exists
-    DomainBase existingDomain = loadAndVerifyExistence(DomainBase.class, targetId, now);
+    Domain existingDomain = loadAndVerifyExistence(Domain.class, targetId, now);
     Optional<AllocationToken> allocationToken =
         allocationTokenFlowUtils.verifyAllocationTokenIfPresent(
             existingDomain,
@@ -210,7 +210,9 @@ public final class DomainRenewFlow implements TransactionalFlow {
             .setEventTime(newExpirationTime)
             .setRenewalPrice(existingRecurringBillingEvent.getRenewalPrice().orElse(null))
             .setRenewalPriceBehavior(existingRecurringBillingEvent.getRenewalPriceBehavior())
-            .setParent(domainHistoryKey)
+            .setDomainHistoryId(
+                new DomainHistoryId(
+                    domainHistoryKey.getParent().getName(), domainHistoryKey.getId()))
             .build();
     PollMessage.Autorenew newAutorenewPollMessage =
         newAutorenewPollMessage(existingDomain)
@@ -221,7 +223,7 @@ public final class DomainRenewFlow implements TransactionalFlow {
             .build();
     // End the old autorenew billing event and poll message now. This may delete the poll message.
     updateAutorenewRecurrenceEndTime(existingDomain, now);
-    DomainBase newDomain =
+    Domain newDomain =
         existingDomain
             .asBuilder()
             .setLastEppUpdateTime(now)
@@ -273,7 +275,7 @@ public final class DomainRenewFlow implements TransactionalFlow {
   }
 
   private DomainHistory buildDomainHistory(
-      DomainBase newDomain, DateTime now, Period period, Duration renewGracePeriod) {
+      Domain newDomain, DateTime now, Period period, Duration renewGracePeriod) {
     Optional<MetadataExtension> metadataExtensionOpt =
         eppInput.getSingleExtension(MetadataExtension.class);
     if (metadataExtensionOpt.isPresent()) {
@@ -297,10 +299,8 @@ public final class DomainRenewFlow implements TransactionalFlow {
         .build();
   }
 
-  private void verifyRenewAllowed(
-      Optional<AuthInfo> authInfo,
-      DomainBase existingDomain,
-      Renew command) throws EppException {
+  private void verifyRenewAllowed(Optional<AuthInfo> authInfo, Domain existingDomain, Renew command)
+      throws EppException {
     verifyOptionalAuthInfo(authInfo, existingDomain);
     verifyNoDisallowedStatuses(existingDomain, RENEW_DISALLOWED_STATUSES);
     if (!isSuperuser) {
@@ -332,7 +332,8 @@ public final class DomainRenewFlow implements TransactionalFlow {
         .setEventTime(now)
         .setAllocationToken(allocationToken.map(AllocationToken::createVKey).orElse(null))
         .setBillingTime(now.plus(Registry.get(tld).getRenewGracePeriodLength()))
-        .setParent(domainHistoryKey)
+        .setDomainHistoryId(
+            new DomainHistoryId(domainHistoryKey.getParent().getName(), domainHistoryKey.getId()))
         .build();
   }
 

core/src/main/java/google/registry/flows/domain/DomainRestoreRequestFlow.java

@@ -50,7 +50,7 @@ import google.registry.model.ImmutableObject;
 import google.registry.model.billing.BillingEvent;
 import google.registry.model.billing.BillingEvent.OneTime;
 import google.registry.model.billing.BillingEvent.Reason;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainCommand.Update;
 import google.registry.model.domain.DomainHistory;
 import google.registry.model.domain.DomainHistory.DomainHistoryId;
@@ -140,7 +140,7 @@ public final class DomainRestoreRequestFlow implements TransactionalFlow {
     extensionManager.validate();
     Update command = (Update) resourceCommand;
     DateTime now = tm().getTransactionTime();
-    DomainBase existingDomain = loadAndVerifyExistence(DomainBase.class, targetId, now);
+    Domain existingDomain = loadAndVerifyExistence(Domain.class, targetId, now);
     boolean isExpired = existingDomain.getRegistrationExpirationTime().isBefore(now);
     FeesAndCredits feesAndCredits =
         pricingLogic.getRestorePrice(
@@ -150,6 +150,8 @@ public final class DomainRestoreRequestFlow implements TransactionalFlow {
     verifyRestoreAllowed(command, existingDomain, feeUpdate, feesAndCredits, now);
     Key<DomainHistory> domainHistoryKey = createHistoryKey(existingDomain, DomainHistory.class);
     historyBuilder.setId(domainHistoryKey.getId());
+    DomainHistoryId domainHistoryId =
+        new DomainHistoryId(domainHistoryKey.getParent().getName(), domainHistoryKey.getId());
     ImmutableSet.Builder<ImmutableObject> entitiesToSave = new ImmutableSet.Builder<>();
 
     DateTime newExpirationTime =
@@ -158,17 +160,17 @@ public final class DomainRestoreRequestFlow implements TransactionalFlow {
     // a year and bill for it immediately, with no grace period.
     if (isExpired) {
       entitiesToSave.add(
-          createRenewBillingEvent(domainHistoryKey, feesAndCredits.getRenewCost(), now));
+          createRenewBillingEvent(domainHistoryId, feesAndCredits.getRenewCost(), now));
     }
     // Always bill for the restore itself.
     entitiesToSave.add(
-        createRestoreBillingEvent(domainHistoryKey, feesAndCredits.getRestoreCost(), now));
+        createRestoreBillingEvent(domainHistoryId, feesAndCredits.getRestoreCost(), now));
 
     BillingEvent.Recurring autorenewEvent =
         newAutorenewBillingEvent(existingDomain)
             .setEventTime(newExpirationTime)
             .setRecurrenceEndTime(END_OF_TIME)
-            .setParent(domainHistoryKey)
+            .setDomainHistoryId(domainHistoryId)
             .build();
     PollMessage.Autorenew autorenewPollMessage =
         newAutorenewPollMessage(existingDomain)
@@ -178,7 +180,7 @@ public final class DomainRestoreRequestFlow implements TransactionalFlow {
                 new DomainHistoryId(
                     domainHistoryKey.getParent().getName(), domainHistoryKey.getId()))
             .build();
-    DomainBase newDomain =
+    Domain newDomain =
         performRestore(
             existingDomain,
             newExpirationTime,
@@ -197,7 +199,7 @@ public final class DomainRestoreRequestFlow implements TransactionalFlow {
         .build();
   }
 
-  private DomainHistory buildDomainHistory(DomainBase newDomain, DateTime now) {
+  private DomainHistory buildDomainHistory(Domain newDomain, DateTime now) {
     return historyBuilder
         .setType(DOMAIN_RESTORE)
         .setDomain(newDomain)
@@ -210,10 +212,11 @@ public final class DomainRestoreRequestFlow implements TransactionalFlow {
 
   private void verifyRestoreAllowed(
       Update command,
-      DomainBase existingDomain,
+      Domain existingDomain,
       Optional<FeeUpdateCommandExtension> feeUpdate,
       FeesAndCredits feesAndCredits,
-      DateTime now) throws EppException {
+      DateTime now)
+      throws EppException {
     verifyOptionalAuthInfo(authInfo, existingDomain);
     if (!isSuperuser) {
       verifyResourceOwnership(registrarId, existingDomain);
@@ -233,8 +236,8 @@ public final class DomainRestoreRequestFlow implements TransactionalFlow {
     validateFeeChallenge(targetId, now, feeUpdate, feesAndCredits);
   }
 
-  private static DomainBase performRestore(
-      DomainBase existingDomain,
+  private static Domain performRestore(
+      Domain existingDomain,
       DateTime newExpirationTime,
       BillingEvent.Recurring autorenewEvent,
       PollMessage.Autorenew autorenewPollMessage,
@@ -259,19 +262,17 @@ public final class DomainRestoreRequestFlow implements TransactionalFlow {
   }
 
   private OneTime createRenewBillingEvent(
-      Key<DomainHistory> domainHistoryKey, Money renewCost, DateTime now) {
-    return prepareBillingEvent(domainHistoryKey, renewCost, now).setReason(Reason.RENEW).build();
+      DomainHistoryId domainHistoryId, Money renewCost, DateTime now) {
+    return prepareBillingEvent(domainHistoryId, renewCost, now).setReason(Reason.RENEW).build();
   }
 
   private BillingEvent.OneTime createRestoreBillingEvent(
-      Key<DomainHistory> domainHistoryKey, Money restoreCost, DateTime now) {
-    return prepareBillingEvent(domainHistoryKey, restoreCost, now)
-        .setReason(Reason.RESTORE)
-        .build();
+      DomainHistoryId domainHistoryId, Money restoreCost, DateTime now) {
+    return prepareBillingEvent(domainHistoryId, restoreCost, now).setReason(Reason.RESTORE).build();
   }
 
   private OneTime.Builder prepareBillingEvent(
-      Key<DomainHistory> domainHistoryKey, Money cost, DateTime now) {
+      DomainHistoryId domainHistoryId, Money cost, DateTime now) {
     return new BillingEvent.OneTime.Builder()
         .setTargetId(targetId)
         .setRegistrarId(registrarId)
@@ -279,7 +280,7 @@ public final class DomainRestoreRequestFlow implements TransactionalFlow {
         .setBillingTime(now)
         .setPeriodYears(1)
         .setCost(cost)
-        .setParent(domainHistoryKey);
+        .setDomainHistoryId(domainHistoryId);
   }
 
   private static ImmutableList<FeeTransformResponseExtension> createResponseExtensions(

core/src/main/java/google/registry/flows/domain/DomainTransferApproveFlow.java

@@ -49,7 +49,7 @@ import google.registry.model.ImmutableObject;
 import google.registry.model.billing.BillingEvent;
 import google.registry.model.billing.BillingEvent.Flag;
 import google.registry.model.billing.BillingEvent.Reason;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainHistory;
 import google.registry.model.domain.DomainHistory.DomainHistoryId;
 import google.registry.model.domain.GracePeriod;
@@ -100,7 +100,7 @@ public final class DomainTransferApproveFlow implements TransactionalFlow {
 
   /**
    * The logic in this flow, which handles client approvals, very closely parallels the logic in
-   * {@link DomainBase#cloneProjectedAtTime} which handles implicit server approvals.
+   * {@link Domain#cloneProjectedAtTime} which handles implicit server approvals.
    */
   @Override
   public EppResponse run() throws EppException {
@@ -108,7 +108,7 @@ public final class DomainTransferApproveFlow implements TransactionalFlow {
     validateRegistrarIsLoggedIn(registrarId);
     extensionManager.validate();
     DateTime now = tm().getTransactionTime();
-    DomainBase existingDomain = loadAndVerifyExistence(DomainBase.class, targetId, now);
+    Domain existingDomain = loadAndVerifyExistence(Domain.class, targetId, now);
     verifyOptionalAuthInfo(authInfo, existingDomain);
     verifyHasPendingTransfer(existingDomain);
     verifyResourceOwnership(registrarId, existingDomain);
@@ -123,7 +123,7 @@ public final class DomainTransferApproveFlow implements TransactionalFlow {
     Key<DomainHistory> domainHistoryKey = createHistoryKey(existingDomain, DomainHistory.class);
     historyBuilder.setId(domainHistoryKey.getId());
     Optional<BillingEvent.OneTime> billingEvent =
-        (transferData.getTransferPeriod().getValue() == 0)
+        transferData.getTransferPeriod().getValue() == 0
             ? Optional.empty()
             : Optional.of(
                 new BillingEvent.OneTime.Builder()
@@ -134,7 +134,9 @@ public final class DomainTransferApproveFlow implements TransactionalFlow {
                     .setCost(getDomainRenewCost(targetId, transferData.getTransferRequestTime(), 1))
                     .setEventTime(now)
                     .setBillingTime(now.plus(Registry.get(tld).getTransferGracePeriodLength()))
-                    .setParent(domainHistoryKey)
+                    .setDomainHistoryId(
+                        new DomainHistoryId(
+                            domainHistoryKey.getParent().getName(), domainHistoryKey.getId()))
                     .build());
     ImmutableList.Builder<ImmutableObject> entitiesToSave = new ImmutableList.Builder<>();
     // If we are within an autorenew grace period, cancel the autorenew billing event and don't
@@ -150,7 +152,11 @@ public final class DomainTransferApproveFlow implements TransactionalFlow {
       if (billingEvent.isPresent()) {
         entitiesToSave.add(
             BillingEvent.Cancellation.forGracePeriod(
-                autorenewGrace, now, domainHistoryKey, targetId));
+                autorenewGrace,
+                now,
+                new DomainHistoryId(
+                    domainHistoryKey.getParent().getName(), domainHistoryKey.getId()),
+                targetId));
       }
     }
     // Close the old autorenew event and poll message at the transfer time (aka now). This may end
@@ -167,7 +173,9 @@ public final class DomainTransferApproveFlow implements TransactionalFlow {
             .setRegistrarId(gainingRegistrarId)
             .setEventTime(newExpirationTime)
             .setRecurrenceEndTime(END_OF_TIME)
-            .setParent(domainHistoryKey)
+            .setDomainHistoryId(
+                new DomainHistoryId(
+                    domainHistoryKey.getParent().getName(), domainHistoryKey.getId()))
             .build();
     // Create a new autorenew poll message.
     PollMessage.Autorenew gainingClientAutorenewPollMessage =
@@ -182,9 +190,9 @@ public final class DomainTransferApproveFlow implements TransactionalFlow {
                     domainHistoryKey.getParent().getName(), domainHistoryKey.getId()))
             .build();
     // Construct the post-transfer domain.
-    DomainBase partiallyApprovedDomain =
+    Domain partiallyApprovedDomain =
         approvePendingTransfer(existingDomain, TransferStatus.CLIENT_APPROVED, now);
-    DomainBase newDomain =
+    Domain newDomain =
         partiallyApprovedDomain
             .asBuilder()
             // Update the transferredRegistrationExpirationTime here since approvePendingTransfer()
@@ -238,7 +246,7 @@ public final class DomainTransferApproveFlow implements TransactionalFlow {
   }
 
   private DomainHistory buildDomainHistory(
-      DomainBase newDomain, Registry registry, DateTime now, String gainingRegistrarId) {
+      Domain newDomain, Registry registry, DateTime now, String gainingRegistrarId) {
     ImmutableSet<DomainTransactionRecord> cancelingRecords =
         createCancelingRecords(
             newDomain,

core/src/main/java/google/registry/flows/domain/DomainTransferCancelFlow.java

@@ -40,7 +40,7 @@ import google.registry.flows.FlowModule.Superuser;
 import google.registry.flows.FlowModule.TargetId;
 import google.registry.flows.TransactionalFlow;
 import google.registry.flows.annotations.ReportingSpec;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainHistory;
 import google.registry.model.domain.metadata.MetadataExtension;
 import google.registry.model.eppcommon.AuthInfo;
@@ -90,7 +90,7 @@ public final class DomainTransferCancelFlow implements TransactionalFlow {
     validateRegistrarIsLoggedIn(registrarId);
     extensionManager.validate();
     DateTime now = tm().getTransactionTime();
-    DomainBase existingDomain = loadAndVerifyExistence(DomainBase.class, targetId, now);
+    Domain existingDomain = loadAndVerifyExistence(Domain.class, targetId, now);
     verifyOptionalAuthInfo(authInfo, existingDomain);
     verifyHasPendingTransfer(existingDomain);
     verifyTransferInitiator(registrarId, existingDomain);
@@ -104,7 +104,7 @@ public final class DomainTransferCancelFlow implements TransactionalFlow {
         .setId(domainHistoryKey.getId())
         .setOtherRegistrarId(existingDomain.getTransferData().getLosingRegistrarId());
 
-    DomainBase newDomain =
+    Domain newDomain =
         denyPendingTransfer(existingDomain, TransferStatus.CLIENT_CANCELLED, now, registrarId);
     DomainHistory domainHistory = buildDomainHistory(newDomain, registry, now);
     tm().putAll(
@@ -123,7 +123,7 @@ public final class DomainTransferCancelFlow implements TransactionalFlow {
         .build();
   }
 
-  private DomainHistory buildDomainHistory(DomainBase newDomain, Registry registry, DateTime now) {
+  private DomainHistory buildDomainHistory(Domain newDomain, Registry registry, DateTime now) {
     ImmutableSet<DomainTransactionRecord> cancelingRecords =
         createCancelingRecords(
             newDomain,

core/src/main/java/google/registry/flows/domain/DomainTransferQueryFlow.java

@@ -28,7 +28,7 @@ import google.registry.flows.ResourceFlowUtils;
 import google.registry.flows.annotations.ReportingSpec;
 import google.registry.flows.exceptions.NoTransferHistoryToQueryException;
 import google.registry.flows.exceptions.NotAuthorizedToViewTransferException;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.eppcommon.AuthInfo;
 import google.registry.model.eppoutput.EppResponse;
 import google.registry.model.reporting.IcannReportingTypes.ActivityReportField;
@@ -71,7 +71,7 @@ public final class DomainTransferQueryFlow implements Flow {
     validateRegistrarIsLoggedIn(registrarId);
     extensionManager.validate(); // There are no legal extensions for this flow.
     DateTime now = clock.nowUtc();
-    DomainBase domain = loadAndVerifyExistence(DomainBase.class, targetId, now);
+    Domain domain = loadAndVerifyExistence(Domain.class, targetId, now);
     verifyOptionalAuthInfo(authInfo, domain);
     // Most of the fields on the transfer response are required, so there's no way to return valid
     // XML if the object has never been transferred (and hence the fields aren't populated).

core/src/main/java/google/registry/flows/domain/DomainTransferRejectFlow.java

@@ -42,7 +42,7 @@ import google.registry.flows.FlowModule.Superuser;
 import google.registry.flows.FlowModule.TargetId;
 import google.registry.flows.TransactionalFlow;
 import google.registry.flows.annotations.ReportingSpec;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainHistory;
 import google.registry.model.domain.metadata.MetadataExtension;
 import google.registry.model.eppcommon.AuthInfo;
@@ -92,7 +92,7 @@ public final class DomainTransferRejectFlow implements TransactionalFlow {
     validateRegistrarIsLoggedIn(registrarId);
     extensionManager.validate();
     DateTime now = tm().getTransactionTime();
-    DomainBase existingDomain = loadAndVerifyExistence(DomainBase.class, targetId, now);
+    Domain existingDomain = loadAndVerifyExistence(Domain.class, targetId, now);
     Registry registry = Registry.get(existingDomain.getTld());
     Key<DomainHistory> domainHistoryKey = createHistoryKey(existingDomain, DomainHistory.class);
     historyBuilder
@@ -105,7 +105,7 @@ public final class DomainTransferRejectFlow implements TransactionalFlow {
     if (!isSuperuser) {
       checkAllowedAccessToTld(registrarId, existingDomain.getTld());
     }
-    DomainBase newDomain =
+    Domain newDomain =
         denyPendingTransfer(existingDomain, TransferStatus.CLIENT_REJECTED, now, registrarId);
     DomainHistory domainHistory = buildDomainHistory(newDomain, registry, now);
     tm().putAll(
@@ -124,7 +124,7 @@ public final class DomainTransferRejectFlow implements TransactionalFlow {
         .build();
   }
 
-  private DomainHistory buildDomainHistory(DomainBase newDomain, Registry registry, DateTime now) {
+  private DomainHistory buildDomainHistory(Domain newDomain, Registry registry, DateTime now) {
     ImmutableSet<DomainTransactionRecord> cancelingRecords =
         createCancelingRecords(
             newDomain,

core/src/main/java/google/registry/flows/domain/DomainTransferRequestFlow.java

@@ -52,7 +52,7 @@ import google.registry.flows.exceptions.InvalidTransferPeriodValueException;
 import google.registry.flows.exceptions.ObjectAlreadySponsoredException;
 import google.registry.flows.exceptions.TransferPeriodMustBeOneYearException;
 import google.registry.flows.exceptions.TransferPeriodZeroAndFeeTransferExtensionException;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainCommand.Transfer;
 import google.registry.model.domain.DomainHistory;
 import google.registry.model.domain.Period;
@@ -149,7 +149,7 @@ public final class DomainTransferRequestFlow implements TransactionalFlow {
     verifyRegistrarIsActive(gainingClientId);
     extensionManager.validate();
     DateTime now = tm().getTransactionTime();
-    DomainBase existingDomain = loadAndVerifyExistence(DomainBase.class, targetId, now);
+    Domain existingDomain = loadAndVerifyExistence(Domain.class, targetId, now);
     Optional<DomainTransferRequestSuperuserExtension> superuserExtension =
         eppInput.getSingleExtension(DomainTransferRequestSuperuserExtension.class);
     Period period =
@@ -190,7 +190,7 @@ public final class DomainTransferRequestFlow implements TransactionalFlow {
     //
     // See b/19430703#comment17 and https://www.icann.org/news/advisory-2002-06-06-en for the
     // policy documentation for transfers subsuming autorenews within the autorenew grace period.
-    DomainBase domainAtTransferTime = existingDomain.cloneProjectedAtTime(automaticTransferTime);
+    Domain domainAtTransferTime = existingDomain.cloneProjectedAtTime(automaticTransferTime);
     // The new expiration time if there is a server approval.
     DateTime serverApproveNewExpirationTime =
         computeExDateForApprovalTime(domainAtTransferTime, automaticTransferTime, period);
@@ -231,7 +231,7 @@ public final class DomainTransferRequestFlow implements TransactionalFlow {
     // cloneProjectedAtTime() will replace these old autorenew entities with the server approve ones
     // that we've created in this flow and stored in pendingTransferData.
     updateAutorenewRecurrenceEndTime(existingDomain, automaticTransferTime);
-    DomainBase newDomain =
+    Domain newDomain =
         existingDomain
             .asBuilder()
             .setTransferData(pendingTransferData)
@@ -255,7 +255,7 @@ public final class DomainTransferRequestFlow implements TransactionalFlow {
   }
 
   private void verifyTransferAllowed(
-      DomainBase existingDomain,
+      Domain existingDomain,
       Period period,
       DateTime now,
       Optional<DomainTransferRequestSuperuserExtension> superuserExtension)
@@ -320,7 +320,7 @@ public final class DomainTransferRequestFlow implements TransactionalFlow {
   }
 
   private DomainHistory buildDomainHistory(
-      DomainBase newDomain, Registry registry, DateTime now, Period period) {
+      Domain newDomain, Registry registry, DateTime now, Period period) {
     return historyBuilder
         .setType(DOMAIN_TRANSFER_REQUEST)
         .setPeriod(period)
@@ -337,7 +337,7 @@ public final class DomainTransferRequestFlow implements TransactionalFlow {
   }
 
   private DomainTransferResponse createResponse(
-      Period period, DomainBase existingDomain, DomainBase newDomain, DateTime now) {
+      Period period, Domain existingDomain, Domain newDomain, DateTime now) {
     // If the registration were approved this instant, this is what the new expiration would be,
     // because we cap at 10 years from the moment of approval. This is different than the server
     // approval new expiration time, which is capped at 10 years from the server approve time.

core/src/main/java/google/registry/flows/domain/DomainTransferUtils.java

@@ -24,7 +24,7 @@ import com.googlecode.objectify.Key;
 import google.registry.model.billing.BillingEvent;
 import google.registry.model.billing.BillingEvent.Flag;
 import google.registry.model.billing.BillingEvent.Reason;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainHistory;
 import google.registry.model.domain.DomainHistory.DomainHistoryId;
 import google.registry.model.domain.GracePeriod;
@@ -109,7 +109,7 @@ public final class DomainTransferUtils {
       DateTime automaticTransferTime,
       DateTime serverApproveNewExpirationTime,
       Key<DomainHistory> domainHistoryKey,
-      DomainBase existingDomain,
+      Domain existingDomain,
       Trid trid,
       String gainingRegistrarId,
       Optional<Money> transferCost,
@@ -250,7 +250,8 @@ public final class DomainTransferUtils {
         .setRegistrarId(gainingRegistrarId)
         .setEventTime(serverApproveNewExpirationTime)
         .setRecurrenceEndTime(END_OF_TIME)
-        .setParent(domainHistoryKey)
+        .setDomainHistoryId(
+            new DomainHistoryId(domainHistoryKey.getParent().getName(), domainHistoryKey.getId()))
         .build();
   }
 
@@ -275,17 +276,20 @@ public final class DomainTransferUtils {
       DateTime now,
       Key<DomainHistory> domainHistoryKey,
       String targetId,
-      DomainBase existingDomain,
+      Domain existingDomain,
       Optional<Money> transferCost) {
-    DomainBase domainAtTransferTime =
-        existingDomain.cloneProjectedAtTime(automaticTransferTime);
+    Domain domainAtTransferTime = existingDomain.cloneProjectedAtTime(automaticTransferTime);
     GracePeriod autorenewGracePeriod =
         getOnlyElement(
             domainAtTransferTime.getGracePeriodsOfType(GracePeriodStatus.AUTO_RENEW), null);
     if (autorenewGracePeriod != null && transferCost.isPresent()) {
       return Optional.of(
           BillingEvent.Cancellation.forGracePeriod(
-                  autorenewGracePeriod, now, domainHistoryKey, targetId)
+                  autorenewGracePeriod,
+                  now,
+                  new DomainHistoryId(
+                      domainHistoryKey.getParent().getName(), domainHistoryKey.getId()),
+                  targetId)
               .asBuilder()
               .setEventTime(automaticTransferTime)
               .build());
@@ -308,7 +312,8 @@ public final class DomainTransferUtils {
         .setPeriodYears(1)
         .setEventTime(automaticTransferTime)
         .setBillingTime(automaticTransferTime.plus(registry.getTransferGracePeriodLength()))
-        .setParent(domainHistoryKey)
+        .setDomainHistoryId(
+            new DomainHistoryId(domainHistoryKey.getParent().getName(), domainHistoryKey.getId()))
         .build();
   }
 

core/src/main/java/google/registry/flows/domain/DomainUpdateFlow.java

@@ -67,7 +67,7 @@ import google.registry.model.ImmutableObject;
 import google.registry.model.billing.BillingEvent;
 import google.registry.model.billing.BillingEvent.Reason;
 import google.registry.model.domain.DesignatedContact;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainCommand.Update;
 import google.registry.model.domain.DomainCommand.Update.AddRemove;
 import google.registry.model.domain.DomainCommand.Update.Change;
@@ -173,11 +173,11 @@ public final class DomainUpdateFlow implements TransactionalFlow {
     extensionManager.validate();
     DateTime now = tm().getTransactionTime();
     Update command = cloneAndLinkReferences((Update) resourceCommand, now);
-    DomainBase existingDomain = loadAndVerifyExistence(DomainBase.class, targetId, now);
+    Domain existingDomain = loadAndVerifyExistence(Domain.class, targetId, now);
     verifyUpdateAllowed(command, existingDomain, now);
     flowCustomLogic.afterValidation(
         AfterValidationParameters.newBuilder().setExistingDomain(existingDomain).build());
-    DomainBase newDomain = performUpdate(command, existingDomain, now);
+    Domain newDomain = performUpdate(command, existingDomain, now);
     DomainHistory domainHistory =
         historyBuilder.setType(DOMAIN_UPDATE).setDomain(newDomain).build();
     validateNewState(newDomain);
@@ -204,7 +204,7 @@ public final class DomainUpdateFlow implements TransactionalFlow {
   }
 
   /** Fail if the object doesn't exist or was deleted. */
-  private void verifyUpdateAllowed(Update command, DomainBase existingDomain, DateTime now)
+  private void verifyUpdateAllowed(Update command, Domain existingDomain, DateTime now)
       throws EppException {
     verifyOptionalAuthInfo(authInfo, existingDomain);
     AddRemove add = command.getInnerAdd();
@@ -233,8 +233,7 @@ public final class DomainUpdateFlow implements TransactionalFlow {
         tld, add.getNameserverFullyQualifiedHostNames());
   }
 
-  private DomainBase performUpdate(Update command, DomainBase domain, DateTime now)
-      throws EppException {
+  private Domain performUpdate(Update command, Domain domain, DateTime now) throws EppException {
     AddRemove add = command.getInnerAdd();
     AddRemove remove = command.getInnerRemove();
     checkSameValuesNotAddedAndRemoved(add.getNameservers(), remove.getNameservers());
@@ -251,7 +250,7 @@ public final class DomainUpdateFlow implements TransactionalFlow {
         Sets.union(Sets.difference(domain.getContacts(), remove.getContacts()), add.getContacts());
     validateNoDuplicateContacts(newContacts);
 
-    DomainBase.Builder domainBuilder =
+    Domain.Builder domainBuilder =
         domain
             .asBuilder()
             // Handle the secDNS extension. As dsData in secDnsUpdate is read from EPP input and
@@ -293,7 +292,7 @@ public final class DomainUpdateFlow implements TransactionalFlow {
     }
   }
 
-  private void validateNewState(DomainBase newDomain) throws EppException {
+  private void validateNewState(Domain newDomain) throws EppException {
     validateRequiredContactsPresent(newDomain.getRegistrant(), newDomain.getContacts());
     validateDsData(newDomain.getDsData());
     validateNameserversCountForTld(
@@ -304,7 +303,7 @@ public final class DomainUpdateFlow implements TransactionalFlow {
 
   /** Some status updates cost money. Bill only once no matter how many of them are changed. */
   private Optional<BillingEvent.OneTime> createBillingEventForStatusUpdates(
-      DomainBase existingDomain, DomainBase newDomain, DomainHistory historyEntry, DateTime now) {
+      Domain existingDomain, Domain newDomain, DomainHistory historyEntry, DateTime now) {
     Optional<MetadataExtension> metadataExtension =
         eppInput.getSingleExtension(MetadataExtension.class);
     if (metadataExtension.isPresent() && metadataExtension.get().getRequestedByRegistrar()) {
@@ -320,7 +319,7 @@ public final class DomainUpdateFlow implements TransactionalFlow {
                   .setCost(Registry.get(existingDomain.getTld()).getServerStatusChangeCost())
                   .setEventTime(now)
                   .setBillingTime(now)
-                  .setParent(historyEntry)
+                  .setDomainHistory(historyEntry)
                   .build());
         }
       }
@@ -330,7 +329,7 @@ public final class DomainUpdateFlow implements TransactionalFlow {
 
   /** Enqueues a poll message iff a superuser is adding/removing server statuses. */
   private Optional<PollMessage.OneTime> createPollMessageForServerStatusUpdates(
-      DomainBase existingDomain, DomainBase newDomain, DomainHistory historyEntry, DateTime now) {
+      Domain existingDomain, Domain newDomain, DomainHistory historyEntry, DateTime now) {
     if (registrarId.equals(existingDomain.getPersistedCurrentSponsorRegistrarId())) {
       // Don't send a poll message when a superuser registrar is updating its own domain.
       return Optional.empty();

core/src/main/java/google/registry/flows/domain/token/AllocationTokenCustomLogic.java

@@ -19,7 +19,7 @@ import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Maps;
 import com.google.common.net.InternetDomainName;
 import google.registry.flows.EppException;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainCommand;
 import google.registry.model.domain.token.AllocationToken;
 import google.registry.model.tld.Registry;
@@ -46,7 +46,7 @@ public class AllocationTokenCustomLogic {
 
   /** Performs additional custom logic for validating a token on an existing domain. */
   public AllocationToken validateToken(
-      DomainBase domain, AllocationToken token, Registry registry, String registrarId, DateTime now)
+      Domain domain, AllocationToken token, Registry registry, String registrarId, DateTime now)
       throws EppException {
     // Do nothing.
     return token;

core/src/main/java/google/registry/flows/domain/token/AllocationTokenFlowUtils.java

@@ -26,7 +26,7 @@ import google.registry.flows.EppException;
 import google.registry.flows.EppException.AssociationProhibitsOperationException;
 import google.registry.flows.EppException.AuthorizationErrorException;
 import google.registry.flows.EppException.StatusProhibitsOperationException;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainCommand;
 import google.registry.model.domain.token.AllocationToken;
 import google.registry.model.domain.token.AllocationToken.TokenStatus;
@@ -171,7 +171,7 @@ public class AllocationTokenFlowUtils {
 
   /** Verifies and returns the allocation token if one is specified, otherwise does nothing. */
   public Optional<AllocationToken> verifyAllocationTokenIfPresent(
-      DomainBase existingDomain,
+      Domain existingDomain,
       Registry registry,
       String registrarId,
       DateTime now,

core/src/main/java/google/registry/flows/host/HostCreateFlow.java

@@ -41,7 +41,7 @@ import google.registry.flows.annotations.ReportingSpec;
 import google.registry.flows.exceptions.ResourceAlreadyExistsForThisClientException;
 import google.registry.flows.exceptions.ResourceCreateContentionException;
 import google.registry.model.ImmutableObject;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.metadata.MetadataExtension;
 import google.registry.model.eppinput.ResourceCommand;
 import google.registry.model.eppoutput.CreateData.HostCreateData;
@@ -109,7 +109,7 @@ public final class HostCreateFlow implements TransactionalFlow {
     // The superordinate domain of the host object if creating an in-bailiwick host, or null if
     // creating an external host. This is looked up before we actually create the Host object so
     // we can detect error conditions earlier.
-    Optional<DomainBase> superordinateDomain =
+    Optional<Domain> superordinateDomain =
         lookupSuperordinateDomain(validateHostName(targetId), now);
     verifySuperordinateDomainNotInPendingDelete(superordinateDomain.orElse(null));
     verifySuperordinateDomainOwnership(registrarId, superordinateDomain.orElse(null));
@@ -128,7 +128,7 @@ public final class HostCreateFlow implements TransactionalFlow {
             .setHostName(targetId)
             .setInetAddresses(command.getInetAddresses())
             .setRepoId(createRepoId(allocateId(), roidSuffix))
-            .setSuperordinateDomain(superordinateDomain.map(DomainBase::createVKey).orElse(null))
+            .setSuperordinateDomain(superordinateDomain.map(Domain::createVKey).orElse(null))
             .build();
     historyBuilder.setType(HOST_CREATE).setHost(newHost);
     ImmutableSet<ImmutableObject> entitiesToSave =

core/src/main/java/google/registry/flows/host/HostFlowUtils.java

@@ -29,7 +29,7 @@ import google.registry.flows.EppException.ParameterValuePolicyErrorException;
 import google.registry.flows.EppException.ParameterValueRangeErrorException;
 import google.registry.flows.EppException.ParameterValueSyntaxErrorException;
 import google.registry.flows.EppException.StatusProhibitsOperationException;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.eppcommon.StatusValue;
 import google.registry.util.Idn;
 import java.util.Optional;
@@ -77,8 +77,8 @@ public class HostFlowUtils {
     }
   }
 
-  /** Return the {@link DomainBase} this host is subordinate to, or null for external hosts. */
-  public static Optional<DomainBase> lookupSuperordinateDomain(
+  /** Return the {@link Domain} this host is subordinate to, or null for external hosts. */
+  public static Optional<Domain> lookupSuperordinateDomain(
       InternetDomainName hostName, DateTime now) throws EppException {
     Optional<InternetDomainName> tld = findTldForName(hostName);
     if (!tld.isPresent()) {
@@ -90,8 +90,7 @@ public class HostFlowUtils {
         hostName.parts().stream()
             .skip(hostName.parts().size() - (tld.get().parts().size() + 1))
             .collect(joining("."));
-    Optional<DomainBase> superordinateDomain =
-        loadByForeignKey(DomainBase.class, domainName, now);
+    Optional<Domain> superordinateDomain = loadByForeignKey(Domain.class, domainName, now);
     if (!superordinateDomain.isPresent() || !isActive(superordinateDomain.get(), now)) {
       throw new SuperordinateDomainDoesNotExistException(domainName);
     }
@@ -101,12 +100,12 @@ public class HostFlowUtils {
   /** Superordinate domain for this hostname does not exist. */
   static class SuperordinateDomainDoesNotExistException extends ObjectDoesNotExistException {
     public SuperordinateDomainDoesNotExistException(String domainName) {
-      super(DomainBase.class, domainName);
+      super(Domain.class, domainName);
     }
   }
 
   /** Ensure that the superordinate domain is sponsored by the provided registrar ID. */
-  static void verifySuperordinateDomainOwnership(String registrarId, DomainBase superordinateDomain)
+  static void verifySuperordinateDomainOwnership(String registrarId, Domain superordinateDomain)
       throws EppException {
     if (superordinateDomain != null
         && !registrarId.equals(superordinateDomain.getCurrentSponsorRegistrarId())) {
@@ -122,7 +121,7 @@ public class HostFlowUtils {
   }
 
   /** Ensure that the superordinate domain is not in pending delete. */
-  static void verifySuperordinateDomainNotInPendingDelete(DomainBase superordinateDomain)
+  static void verifySuperordinateDomainNotInPendingDelete(Domain superordinateDomain)
       throws EppException {
     if ((superordinateDomain != null)
         && superordinateDomain.getStatusValues().contains(StatusValue.PENDING_DELETE)) {

core/src/main/java/google/registry/flows/host/HostInfoFlow.java

@@ -27,7 +27,7 @@ import google.registry.flows.Flow;
 import google.registry.flows.FlowModule.RegistrarId;
 import google.registry.flows.FlowModule.TargetId;
 import google.registry.flows.annotations.ReportingSpec;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.eppcommon.StatusValue;
 import google.registry.model.eppoutput.EppResponse;
 import google.registry.model.host.HostInfoData;
@@ -76,7 +76,7 @@ public final class HostInfoFlow implements Flow {
     // the client id, last transfer time, and pending transfer status need to be read off of it. If
     // there is no superordinate domain, the host's own values for these fields will be correct.
     if (host.isSubordinate()) {
-      DomainBase superordinateDomain =
+      Domain superordinateDomain =
           tm().transact(
                   () -> tm().loadByKey(host.getSuperordinateDomain()).cloneProjectedAtTime(now));
       hostInfoDataBuilder

core/src/main/java/google/registry/flows/host/HostUpdateFlow.java

@@ -47,7 +47,7 @@ import google.registry.flows.annotations.ReportingSpec;
 import google.registry.flows.exceptions.ResourceHasClientUpdateProhibitedException;
 import google.registry.model.EppResource;
 import google.registry.model.ImmutableObject;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.metadata.MetadataExtension;
 import google.registry.model.eppcommon.StatusValue;
 import google.registry.model.eppinput.ResourceCommand;
@@ -137,12 +137,12 @@ public final class HostUpdateFlow implements TransactionalFlow {
     boolean isHostRename = suppliedNewHostName != null;
     String oldHostName = targetId;
     String newHostName = firstNonNull(suppliedNewHostName, oldHostName);
-    DomainBase oldSuperordinateDomain =
+    Domain oldSuperordinateDomain =
         existingHost.isSubordinate()
             ? tm().loadByKey(existingHost.getSuperordinateDomain()).cloneProjectedAtTime(now)
             : null;
     // Note that lookupSuperordinateDomain calls cloneProjectedAtTime on the domain for us.
-    Optional<DomainBase> newSuperordinateDomain =
+    Optional<Domain> newSuperordinateDomain =
         lookupSuperordinateDomain(validateHostName(newHostName), now);
     verifySuperordinateDomainNotInPendingDelete(newSuperordinateDomain.orElse(null));
     EppResource owningResource = firstNonNull(oldSuperordinateDomain, existingHost);
@@ -155,8 +155,8 @@ public final class HostUpdateFlow implements TransactionalFlow {
     AddRemove remove = command.getInnerRemove();
     checkSameValuesNotAddedAndRemoved(add.getStatusValues(), remove.getStatusValues());
     checkSameValuesNotAddedAndRemoved(add.getInetAddresses(), remove.getInetAddresses());
-    VKey<DomainBase> newSuperordinateDomainKey =
-        newSuperordinateDomain.map(DomainBase::createVKey).orElse(null);
+    VKey<Domain> newSuperordinateDomainKey =
+        newSuperordinateDomain.map(Domain::createVKey).orElse(null);
     // If the superordinateDomain field is changing, set the lastSuperordinateChange to now.
     DateTime lastSuperordinateChange =
         Objects.equals(newSuperordinateDomainKey, existingHost.getSuperordinateDomain())
@@ -211,10 +211,10 @@ public final class HostUpdateFlow implements TransactionalFlow {
   private void verifyUpdateAllowed(
       Update command,
       HostResource existingHost,
-      DomainBase newSuperordinateDomain,
+      Domain newSuperordinateDomain,
       EppResource owningResource,
       boolean isHostRename)
-          throws EppException {
+      throws EppException {
     if (!isSuperuser) {
       // Verify that the host belongs to this registrar, either directly or because it is currently
       // subordinate to a domain owned by this registrar.

core/src/main/java/google/registry/model/Buildable.java

@@ -20,6 +20,7 @@ import static google.registry.model.IdService.allocateId;
 import static google.registry.model.ModelUtils.getAllFields;
 
 import com.googlecode.objectify.annotation.Id;
+import google.registry.model.annotations.OfyIdAllocation;
 import google.registry.util.TypeUtils.TypeInstantiator;
 import java.lang.reflect.Field;
 import java.util.Optional;
@@ -59,7 +60,10 @@ public interface Buildable {
         // any entity it has one and only one @Id field in its class hierarchy.
         Field idField =
             getAllFields(instance.getClass()).values().stream()
-                .filter(field -> field.isAnnotationPresent(Id.class))
+                .filter(
+                    field ->
+                        field.isAnnotationPresent(Id.class)
+                            || field.isAnnotationPresent(OfyIdAllocation.class))
                 .findFirst()
                 .orElse(null);
         if (idField != null

core/src/main/java/google/registry/model/EntityClasses.java

@@ -16,12 +16,11 @@ package google.registry.model;
 
 import com.google.common.collect.ImmutableSet;
 import google.registry.model.annotations.DeleteAfterMigration;
-import google.registry.model.billing.BillingEvent;
 import google.registry.model.common.EntityGroupRoot;
 import google.registry.model.common.GaeUserIdConverter;
 import google.registry.model.contact.ContactHistory;
 import google.registry.model.contact.ContactResource;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainHistory;
 import google.registry.model.domain.token.AllocationToken;
 import google.registry.model.host.HostHistory;
@@ -44,13 +43,9 @@ public final class EntityClasses {
   public static final ImmutableSet<Class<? extends ImmutableObject>> ALL_CLASSES =
       ImmutableSet.of(
           AllocationToken.class,
-          BillingEvent.Cancellation.class,
-          BillingEvent.Modification.class,
-          BillingEvent.OneTime.class,
-          BillingEvent.Recurring.class,
           ContactHistory.class,
           ContactResource.class,
-          DomainBase.class,
+          Domain.class,
           DomainHistory.class,
           EntityGroupRoot.class,
           EppResourceIndex.class,

core/src/main/java/google/registry/model/EppResourceUtils.java

@@ -33,7 +33,7 @@ import google.registry.model.EppResource.BuilderWithTransferData;
 import google.registry.model.EppResource.ForeignKeyedEppResource;
 import google.registry.model.EppResource.ResourceWithTransferData;
 import google.registry.model.contact.ContactResource;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.eppcommon.StatusValue;
 import google.registry.model.host.HostResource;
 import google.registry.model.index.ForeignKeyIndex;
@@ -342,7 +342,7 @@ public final class EppResourceUtils {
    * @param now the logical time of the check
    * @param limit the maximum number of returned keys, unlimited if null
    */
-  public static ImmutableSet<VKey<DomainBase>> getLinkedDomainKeys(
+  public static ImmutableSet<VKey<Domain>> getLinkedDomainKeys(
       VKey<? extends EppResource> key, DateTime now, @Nullable Integer limit) {
     checkArgument(
         key.getKind().equals(ContactResource.class) || key.getKind().equals(HostResource.class),
@@ -350,16 +350,16 @@ public final class EppResourceUtils {
         key);
     boolean isContactKey = key.getKind().equals(ContactResource.class);
     if (tm().isOfy()) {
-      com.googlecode.objectify.cmd.Query<DomainBase> query =
+      com.googlecode.objectify.cmd.Query<Domain> query =
           auditedOfy()
               .load()
-              .type(DomainBase.class)
+              .type(Domain.class)
               .filter(isContactKey ? "allContacts.contact" : "nsHosts", key.getOfyKey())
               .filter("deletionTime >", now);
       if (limit != null) {
         query.limit(limit);
       }
-      return query.keys().list().stream().map(DomainBase::createVKey).collect(toImmutableSet());
+      return query.keys().list().stream().map(Domain::createVKey).collect(toImmutableSet());
     } else {
       return tm().transact(
               () -> {
@@ -382,16 +382,15 @@ public final class EppResourceUtils {
                   query.setMaxResults(limit);
                 }
                 @SuppressWarnings("unchecked")
-                ImmutableSet<VKey<DomainBase>> domainBaseKeySet =
-                    (ImmutableSet<VKey<DomainBase>>)
+                ImmutableSet<VKey<Domain>> domainKeySet =
+                    (ImmutableSet<VKey<Domain>>)
                         query
                             .getResultStream()
                             .map(
                                 repoId ->
-                                    DomainBase.createVKey(
-                                        Key.create(DomainBase.class, (String) repoId)))
+                                    Domain.createVKey(Key.create(Domain.class, (String) repoId)))
                             .collect(toImmutableSet());
-                return domainBaseKeySet;
+                return domainKeySet;
               });
     }
   }

core/src/main/java/google/registry/model/ResourceTransferUtils.java

@@ -26,7 +26,7 @@ import google.registry.model.EppResource.BuilderWithTransferData;
 import google.registry.model.EppResource.ForeignKeyedEppResource;
 import google.registry.model.EppResource.ResourceWithTransferData;
 import google.registry.model.contact.ContactResource;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.eppcommon.StatusValue;
 import google.registry.model.eppcommon.Trid;
 import google.registry.model.index.ForeignKeyIndex;
@@ -101,7 +101,7 @@ public final class ResourceTransferUtils {
   }
 
   private static void assertIsContactOrDomain(EppResource eppResource) {
-    checkState(eppResource instanceof ContactResource || eppResource instanceof DomainBase);
+    checkState(eppResource instanceof ContactResource || eppResource instanceof Domain);
   }
 
   /** Update the relevant {@link ForeignKeyIndex} to cache the new deletion time. */

core/src/main/java/google/registry/model/annotations/OfyIdAllocation.java

@@ -0,0 +1,36 @@
+// Copyright 2022 The Nomulus Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package google.registry.model.annotations;
+
+import google.registry.model.IdService;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation to indicate an ID field that needs to be allocated by Ofy.
+ *
+ * <p>This annotation is only used for the field of a {@link google.registry.model.Buildable} class
+ * that was previously annotated by both Ofy's and JPA's {@code @Id} annotations, of which the Ofy
+ * annotation has been removed. The field still needs to be allocated automatically by the builder,
+ * via the {@link IdService#allocateId()}.
+ *
+ * <p>It should be removed after we switch to using SQL to directly allocate IDs.
+ */
+@DeleteAfterMigration
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.FIELD)
+public @interface OfyIdAllocation {}

core/src/main/java/google/registry/model/billing/BillingEvent.java

@@ -18,7 +18,6 @@ import static com.google.common.base.MoreObjects.firstNonNull;
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkState;
-import static google.registry.persistence.transaction.TransactionManagerFactory.tm;
 import static google.registry.util.CollectionUtils.forceEmptyToNull;
 import static google.registry.util.CollectionUtils.nullToEmptyImmutableCopy;
 import static google.registry.util.DateTimeUtils.END_OF_TIME;
@@ -26,31 +25,21 @@ import static google.registry.util.PreconditionsUtils.checkArgumentNotNull;
 
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
-import com.googlecode.objectify.Key;
-import com.googlecode.objectify.annotation.Entity;
-import com.googlecode.objectify.annotation.Id;
-import com.googlecode.objectify.annotation.Ignore;
-import com.googlecode.objectify.annotation.IgnoreSave;
-import com.googlecode.objectify.annotation.Index;
-import com.googlecode.objectify.annotation.Parent;
-import com.googlecode.objectify.condition.IfNull;
 import google.registry.model.Buildable;
 import google.registry.model.ImmutableObject;
 import google.registry.model.UnsafeSerializable;
+import google.registry.model.annotations.OfyIdAllocation;
 import google.registry.model.annotations.ReportedOn;
 import google.registry.model.common.TimeOfYear;
-import google.registry.model.domain.DomainBase;
 import google.registry.model.domain.DomainHistory;
+import google.registry.model.domain.DomainHistory.DomainHistoryId;
 import google.registry.model.domain.GracePeriod;
 import google.registry.model.domain.rgp.GracePeriodStatus;
 import google.registry.model.domain.token.AllocationToken;
 import google.registry.model.transfer.TransferData.TransferServerApproveEntity;
-import google.registry.persistence.BillingVKey.BillingEventVKey;
-import google.registry.persistence.BillingVKey.BillingRecurrenceVKey;
 import google.registry.persistence.VKey;
 import google.registry.persistence.WithLongVKey;
 import google.registry.persistence.converter.JodaMoneyType;
-import java.util.Objects;
 import java.util.Optional;
 import java.util.Set;
 import javax.annotation.Nullable;
@@ -58,11 +47,13 @@ import javax.persistence.AttributeOverride;
 import javax.persistence.AttributeOverrides;
 import javax.persistence.Column;
 import javax.persistence.Embedded;
+import javax.persistence.Entity;
 import javax.persistence.EnumType;
 import javax.persistence.Enumerated;
+import javax.persistence.Id;
+import javax.persistence.Index;
 import javax.persistence.MappedSuperclass;
-import javax.persistence.PostLoad;
-import javax.persistence.Transient;
+import javax.persistence.Table;
 import org.hibernate.annotations.Columns;
 import org.hibernate.annotations.Type;
 import org.joda.money.Money;
@@ -76,7 +67,7 @@ public abstract class BillingEvent extends ImmutableObject
   /** The reason for the bill, which maps 1:1 to skus in go/registry-billing-skus. */
   public enum Reason {
     CREATE(true),
-    @Deprecated // TODO(b/31676071): remove this legacy value once old data is cleaned up.
+    @Deprecated // DO NOT USE THIS REASON. IT REMAINS BECAUSE OF HISTORICAL DATA. SEE b/31676071.
     ERROR(false),
     FEE_EARLY_ACCESS(true),
     RENEW(true),
@@ -105,9 +96,7 @@ public abstract class BillingEvent extends ImmutableObject
     ALLOCATION,
     ANCHOR_TENANT,
     AUTO_RENEW,
-    /**
-     * Landrush billing events are historical only and are no longer created.
-     */
+    /** Landrush billing events are historical only and are no longer created. */
     LANDRUSH,
     /**
      * This flag is used on create {@link OneTime} billing events for domains that were reserved.
@@ -122,7 +111,7 @@ public abstract class BillingEvent extends ImmutableObject
      * This flag will be added to any {@link OneTime} events that are created via, e.g., an
      * automated process to expand {@link Recurring} events.
      */
-    SYNTHETIC;
+    SYNTHETIC
   }
 
   /**
@@ -149,37 +138,30 @@ public abstract class BillingEvent extends ImmutableObject
      */
     NONPREMIUM,
     /**
-     * This indicates that the renewalPrice in {@link BillingEvent.Recurring} will be used for
-     * domain renewal.
+     * This indicates that the renewalPrice in {@link Recurring} will be used for domain renewal.
      *
      * <p>The renewalPrice has a non-null value iff the price behavior is set to "SPECIFIED". This
      * behavior is used with internal registrations.
      */
-    SPECIFIED;
+    SPECIFIED
   }
 
   /** Entity id. */
-  @Id @javax.persistence.Id Long id;
-
-  @Parent @DoNotHydrate @Transient Key<DomainHistory> parent;
+  @OfyIdAllocation @Id Long id;
 
   /** The registrar to bill. */
-  @Index
   @Column(name = "registrarId", nullable = false)
   String clientId;
 
   /** Revision id of the entry in DomainHistory table that ths bill belongs to. */
-  @Ignore
   @Column(nullable = false)
   Long domainHistoryRevisionId;
 
   /** ID of the EPP resource that the bill is for. */
-  @Ignore
   @Column(nullable = false)
   String domainRepoId;
 
   /** When this event was created. For recurring events, this is also the recurrence start time. */
-  @Index
   @Column(nullable = false)
   DateTime eventTime;
 
@@ -192,17 +174,7 @@ public abstract class BillingEvent extends ImmutableObject
   @Column(name = "domain_name", nullable = false)
   String targetId;
 
-  @Nullable
-  Set<Flag> flags;
-
-  @PostLoad
-  void postLoad() {
-    parent =
-        Key.create(
-            Key.create(DomainBase.class, domainRepoId),
-            DomainHistory.class,
-            domainHistoryRevisionId);
-  }
+  @Nullable Set<Flag> flags;
 
   public String getRegistrarId() {
     return clientId;
@@ -232,8 +204,8 @@ public abstract class BillingEvent extends ImmutableObject
     return targetId;
   }
 
-  public Key<DomainHistory> getParentKey() {
-    return parent;
+  public DomainHistoryId getDomainHistoryId() {
+    return new DomainHistoryId(domainRepoId, domainHistoryRevisionId);
   }
 
   public ImmutableSet<Flag> getFlags() {
@@ -269,16 +241,6 @@ public abstract class BillingEvent extends ImmutableObject
       return thisCastToDerived();
     }
 
-    public B setDomainHistoryRevisionId(long domainHistoryRevisionId) {
-      getInstance().domainHistoryRevisionId = domainHistoryRevisionId;
-      return thisCastToDerived();
-    }
-
-    public B setDomainRepoId(String domainRepoId) {
-      getInstance().domainRepoId = domainRepoId;
-      return thisCastToDerived();
-    }
-
     public B setEventTime(DateTime eventTime) {
       getInstance().eventTime = eventTime;
       return thisCastToDerived();
@@ -294,14 +256,14 @@ public abstract class BillingEvent extends ImmutableObject
       return thisCastToDerived();
     }
 
-    public B setParent(DomainHistory parent) {
-      getInstance().parent = Key.create(parent);
+    public B setDomainHistoryId(DomainHistoryId domainHistoryId) {
+      getInstance().domainHistoryRevisionId = domainHistoryId.getId();
+      getInstance().domainRepoId = domainHistoryId.getDomainRepoId();
       return thisCastToDerived();
     }
 
-    public B setParent(Key<DomainHistory> parentKey) {
-      getInstance().parent = parentKey;
-      return thisCastToDerived();
+    public B setDomainHistory(DomainHistory domainHistory) {
+      return setDomainHistoryId(domainHistory.getDomainHistoryId());
     }
 
     @Override
@@ -311,29 +273,23 @@ public abstract class BillingEvent extends ImmutableObject
       checkNotNull(instance.clientId, "Registrar ID must be set");
       checkNotNull(instance.eventTime, "Event time must be set");
       checkNotNull(instance.targetId, "Target ID must be set");
-      checkNotNull(instance.parent, "Parent must be set");
-      checkNotNull(instance.parent.getParent(), "parent.getParent() must be set");
-      checkNotNull(
-          instance.parent.getParent().getName(), "parent.getParent().getName() must be set");
-      instance.domainHistoryRevisionId = instance.parent.getId();
-      instance.domainRepoId = instance.parent.getParent().getName();
+      checkNotNull(instance.domainHistoryRevisionId, "Domain History Revision ID must be set");
+      checkNotNull(instance.domainRepoId, "Domain Repo ID must be set");
       return super.build();
     }
   }
 
   /** A one-time billable event. */
-  @ReportedOn
-  @Entity
-  @javax.persistence.Entity(name = "BillingEvent")
-  @javax.persistence.Table(
+  @Entity(name = "BillingEvent")
+  @Table(
       indexes = {
-        @javax.persistence.Index(columnList = "registrarId"),
-        @javax.persistence.Index(columnList = "eventTime"),
-        @javax.persistence.Index(columnList = "billingTime"),
-        @javax.persistence.Index(columnList = "syntheticCreationTime"),
-        @javax.persistence.Index(columnList = "domainRepoId"),
-        @javax.persistence.Index(columnList = "allocationToken"),
-        @javax.persistence.Index(columnList = "cancellation_matching_billing_recurrence_id")
+        @Index(columnList = "registrarId"),
+        @Index(columnList = "eventTime"),
+        @Index(columnList = "billingTime"),
+        @Index(columnList = "syntheticCreationTime"),
+        @Index(columnList = "domainRepoId"),
+        @Index(columnList = "allocationToken"),
+        @Index(columnList = "cancellation_matching_billing_recurrence_id")
       })
   @AttributeOverride(name = "id", column = @Column(name = "billing_event_id"))
   @WithLongVKey(compositeKey = true)
@@ -345,15 +301,13 @@ public abstract class BillingEvent extends ImmutableObject
     Money cost;
 
     /** When the cost should be billed. */
-    @Index
     DateTime billingTime;
 
     /**
      * The period in years of the action being billed for, if applicable, otherwise null. Used for
      * financial reporting.
      */
-    @IgnoreSave(IfNull.class)
-    Integer periodYears = null;
+    Integer periodYears;
 
     /**
      * For {@link Flag#SYNTHETIC} events, when this event was persisted to Datastore (i.e. the
@@ -361,11 +315,10 @@ public abstract class BillingEvent extends ImmutableObject
      * needs to be undone, a query on this field will return the complete set of potentially bad
      * events.
      */
-    @Index
     DateTime syntheticCreationTime;
 
     /**
-     * For {@link Flag#SYNTHETIC} events, a {@link Key} to the {@link Recurring} from which this
+     * For {@link Flag#SYNTHETIC} events, a {@link VKey} to the {@link Recurring} from which this
      * {@link OneTime} was created. This is needed in order to properly match billing events against
      * {@link Cancellation}s.
      */
@@ -373,20 +326,17 @@ public abstract class BillingEvent extends ImmutableObject
     VKey<Recurring> cancellationMatchingBillingEvent;
 
     /**
-     * For {@link Flag#SYNTHETIC} events, the {@link DomainHistory} revision ID of the the {@link
+     * For {@link Flag#SYNTHETIC} events, the {@link DomainHistory} revision ID of the {@link
      * Recurring} from which this {@link OneTime} was created. This is needed in order to recreate
      * the {@link VKey} when reading from SQL.
      */
-    @Ignore
     @Column(name = "recurrence_history_revision_id")
     Long recurringEventHistoryRevisionId;
 
     /**
      * The {@link AllocationToken} used in the creation of this event, or null if one was not used.
      */
-    @Index
-    @Nullable
-    VKey<AllocationToken> allocationToken;
+    @Nullable VKey<AllocationToken> allocationToken;
 
     public Money getCost() {
       return cost;
@@ -418,11 +368,11 @@ public abstract class BillingEvent extends ImmutableObject
 
     @Override
     public VKey<OneTime> createVKey() {
-      return VKey.create(OneTime.class, getId(), Key.create(this));
+      return createVKey(getId());
     }
 
-    public static VKey<OneTime> createVKey(Key<OneTime> key) {
-      return VKey.create(OneTime.class, key.getId(), key);
+    public static VKey<OneTime> createVKey(long id) {
+      return VKey.createSql(OneTime.class, id);
     }
 
     @Override
@@ -430,19 +380,6 @@ public abstract class BillingEvent extends ImmutableObject
       return new Builder(clone(this));
     }
 
-    @Override
-    void postLoad() {
-      super.postLoad();
-      if (cancellationMatchingBillingEvent != null) {
-        cancellationMatchingBillingEvent =
-            cancellationMatchingBillingEvent.restoreOfy(
-                DomainBase.class,
-                domainRepoId,
-                DomainHistory.class,
-                recurringEventHistoryRevisionId);
-      }
-    }
-
     /** A builder for {@link OneTime} since it is immutable. */
     public static class Builder extends BillingEvent.Builder<OneTime, Builder> {
 
@@ -475,11 +412,11 @@ public abstract class BillingEvent extends ImmutableObject
       }
 
       public Builder setCancellationMatchingBillingEvent(
-          VKey<Recurring> cancellationMatchingBillingEvent) {
-        getInstance().cancellationMatchingBillingEvent = cancellationMatchingBillingEvent;
-        // getOfyKey() here is safe, recurring billing event VKeys have a valid ofy key.
+          Recurring cancellationMatchingBillingEvent) {
+        getInstance().cancellationMatchingBillingEvent =
+            cancellationMatchingBillingEvent.createVKey();
         getInstance().recurringEventHistoryRevisionId =
-            cancellationMatchingBillingEvent.getOfyKey().getParent().getId();
+            cancellationMatchingBillingEvent.getDomainHistoryRevisionId();
         return this;
       }
 
@@ -511,12 +448,6 @@ public abstract class BillingEvent extends ImmutableObject
                 == (instance.cancellationMatchingBillingEvent != null),
             "Cancellation matching billing event must be set if and only if the SYNTHETIC flag "
                 + "is set.");
-        // getOfyKey() here is safe, billing event VKeys have a valid ofy key.
-        checkState(
-            !instance.getFlags().contains(Flag.SYNTHETIC)
-                || (instance.cancellationMatchingBillingEvent.getOfyKey().getParent().getId()
-                    == instance.recurringEventHistoryRevisionId),
-            "Cancellation matching billing event and its history revision ID does not match.");
         return super.build();
       }
     }
@@ -526,29 +457,26 @@ public abstract class BillingEvent extends ImmutableObject
    * A recurring billable event.
    *
    * <p>Unlike {@link OneTime} events, these do not store an explicit cost, since the cost of the
-   * recurring event might change and each time we bill for it we need to bill at the current cost,
+   * recurring event might change and each time we bill for it, we need to bill at the current cost,
    * not the value that was in use at the time the recurrence was created.
    */
-  @ReportedOn
-  @Entity
-  @javax.persistence.Entity(name = "BillingRecurrence")
-  @javax.persistence.Table(
+  @Entity(name = "BillingRecurrence")
+  @Table(
       indexes = {
-        @javax.persistence.Index(columnList = "registrarId"),
-        @javax.persistence.Index(columnList = "eventTime"),
-        @javax.persistence.Index(columnList = "domainRepoId"),
-        @javax.persistence.Index(columnList = "recurrenceEndTime"),
-        @javax.persistence.Index(columnList = "recurrence_time_of_year")
+        @Index(columnList = "registrarId"),
+        @Index(columnList = "eventTime"),
+        @Index(columnList = "domainRepoId"),
+        @Index(columnList = "recurrenceEndTime"),
+        @Index(columnList = "recurrence_time_of_year")
       })
   @AttributeOverride(name = "id", column = @Column(name = "billing_recurrence_id"))
   @WithLongVKey(compositeKey = true)
   public static class Recurring extends BillingEvent {
 
     /**
-     * The billing event recurs every year between {@link #eventTime} and this time on the
-     * [month, day, time] specified in {@link #recurrenceTimeOfYear}.
+     * The billing event recurs every year between {@link #eventTime} and this time on the [month,
+     * day, time] specified in {@link #recurrenceTimeOfYear}.
      */
-    @Index
     DateTime recurrenceEndTime;
 
     /**
@@ -564,11 +492,9 @@ public abstract class BillingEvent extends ImmutableObject
      * (same day of year, which can be 365 or 366 days later) which is what {@link TimeOfYear} can
      * model, whereas the billing time is a fixed {@link org.joda.time.Duration} later.
      */
-    @Index
     @Embedded
-    @AttributeOverrides({
-      @AttributeOverride(name = "timeString", column = @Column(name = "recurrence_time_of_year"))
-    })
+    @AttributeOverrides(
+        @AttributeOverride(name = "timeString", column = @Column(name = "recurrence_time_of_year")))
     TimeOfYear recurrenceTimeOfYear;
 
     /**
@@ -605,11 +531,11 @@ public abstract class BillingEvent extends ImmutableObject
 
     @Override
     public VKey<Recurring> createVKey() {
-      return VKey.create(Recurring.class, getId(), Key.create(this));
+      return createVKey(getId());
     }
 
-    public static VKey<Recurring> createVKey(Key<Recurring> key) {
-      return VKey.create(Recurring.class, key.getId(), key);
+    public static VKey<Recurring> createVKey(Long id) {
+      return VKey.createSql(Recurring.class, id);
     }
 
     @Override
@@ -647,8 +573,8 @@ public abstract class BillingEvent extends ImmutableObject
         checkNotNull(instance.eventTime);
         checkNotNull(instance.reason);
         checkArgument(
-            (instance.renewalPriceBehavior == RenewalPriceBehavior.SPECIFIED)
-                ^ (instance.renewalPrice == null),
+            instance.renewalPriceBehavior == RenewalPriceBehavior.SPECIFIED
+                ^ instance.renewalPrice == null,
             "Renewal price can have a value if and only if the renewal price behavior is"
                 + " SPECIFIED");
         instance.recurrenceTimeOfYear = TimeOfYear.fromDateTime(instance.eventTime);
@@ -666,47 +592,45 @@ public abstract class BillingEvent extends ImmutableObject
    * preserve the immutability of billing events.
    */
   @ReportedOn
-  @Entity
-  @javax.persistence.Entity(name = "BillingCancellation")
-  @javax.persistence.Table(
+  @Entity(name = "BillingCancellation")
+  @Table(
       indexes = {
-        @javax.persistence.Index(columnList = "registrarId"),
-        @javax.persistence.Index(columnList = "eventTime"),
-        @javax.persistence.Index(columnList = "domainRepoId"),
-        @javax.persistence.Index(columnList = "billingTime"),
-        @javax.persistence.Index(columnList = "billing_event_id"),
-        @javax.persistence.Index(columnList = "billing_recurrence_id")
+        @Index(columnList = "registrarId"),
+        @Index(columnList = "eventTime"),
+        @Index(columnList = "domainRepoId"),
+        @Index(columnList = "billingTime"),
+        @Index(columnList = "billing_event_id"),
+        @Index(columnList = "billing_recurrence_id")
       })
   @AttributeOverride(name = "id", column = @Column(name = "billing_cancellation_id"))
   @WithLongVKey(compositeKey = true)
   public static class Cancellation extends BillingEvent {
 
     /** The billing time of the charge that is being cancelled. */
-    @Index
     DateTime billingTime;
 
     /**
      * The one-time billing event to cancel, or null for autorenew cancellations.
      *
-     * <p>Although the type is {@link Key} the name "ref" is preserved for historical reasons.
+     * <p>Although the type is {@link VKey} the name "ref" is preserved for historical reasons.
      */
-    @IgnoreSave(IfNull.class)
-    BillingEventVKey refOneTime = null;
+    @Column(name = "billing_event_id")
+    VKey<OneTime> refOneTime;
 
     /**
      * The recurring billing event to cancel, or null for non-autorenew cancellations.
      *
-     * <p>Although the type is {@link Key} the name "ref" is preserved for historical reasons.
+     * <p>Although the type is {@link VKey} the name "ref" is preserved for historical reasons.
      */
-    @IgnoreSave(IfNull.class)
-    BillingRecurrenceVKey refRecurring = null;
+    @Column(name = "billing_recurrence_id")
+    VKey<Recurring> refRecurring;
 
     public DateTime getBillingTime() {
       return billingTime;
     }
 
     public VKey<? extends BillingEvent> getEventKey() {
-      return firstNonNull(refOneTime, refRecurring).createVKey();
+      return firstNonNull(refOneTime, refRecurring);
     }
 
     /** The mapping from billable grace period types to originating billing event reasons. */
@@ -723,22 +647,23 @@ public abstract class BillingEvent extends ImmutableObject
      * using the supplied targetId and deriving other metadata (clientId, billing time, and the
      * cancellation reason) from the grace period.
      */
-    public static BillingEvent.Cancellation forGracePeriod(
+    public static Cancellation forGracePeriod(
         GracePeriod gracePeriod,
         DateTime eventTime,
-        Key<DomainHistory> domainHistoryKey,
+        DomainHistoryId domainHistoryId,
         String targetId) {
-      checkArgument(gracePeriod.hasBillingEvent(),
+      checkArgument(
+          gracePeriod.hasBillingEvent(),
           "Cannot create cancellation for grace period without billing event");
-      BillingEvent.Cancellation.Builder builder =
-          new BillingEvent.Cancellation.Builder()
+      Builder builder =
+          new Builder()
               .setReason(checkNotNull(GRACE_PERIOD_TO_REASON.get(gracePeriod.getType())))
               .setTargetId(targetId)
               .setRegistrarId(gracePeriod.getRegistrarId())
               .setEventTime(eventTime)
               // The charge being cancelled will take place at the grace period's expiration time.
               .setBillingTime(gracePeriod.getExpirationTime())
-              .setParent(domainHistoryKey);
+              .setDomainHistoryId(domainHistoryId);
       // Set the grace period's billing event using the appropriate Cancellation builder method.
       if (gracePeriod.getOneTimeBillingEvent() != null) {
         builder.setOneTimeEventKey(gracePeriod.getOneTimeBillingEvent());
@@ -750,11 +675,11 @@ public abstract class BillingEvent extends ImmutableObject
 
     @Override
     public VKey<Cancellation> createVKey() {
-      return VKey.create(Cancellation.class, getId(), Key.create(this));
+      return createVKey(getId());
     }
 
-    public static VKey<Cancellation> createVKey(Key<Cancellation> key) {
-      return VKey.create(Cancellation.class, key.getId(), key);
+    public static VKey<Cancellation> createVKey(long id) {
+      return VKey.createSql(Cancellation.class, id);
     }
 
     @Override
@@ -776,13 +701,13 @@ public abstract class BillingEvent extends ImmutableObject
         return this;
       }
 
-      public Builder setOneTimeEventKey(VKey<BillingEvent.OneTime> eventKey) {
-        getInstance().refOneTime = BillingEventVKey.create(eventKey);
+      public Builder setOneTimeEventKey(VKey<OneTime> eventKey) {
+        getInstance().refOneTime = eventKey;
         return this;
       }
 
-      public Builder setRecurringEventKey(VKey<BillingEvent.Recurring> eventKey) {
-        getInstance().refRecurring = BillingRecurrenceVKey.create(eventKey);
+      public Builder setRecurringEventKey(VKey<Recurring> eventKey) {
+        getInstance().refRecurring = eventKey;
         return this;
       }
 
@@ -791,115 +716,11 @@ public abstract class BillingEvent extends ImmutableObject
         Cancellation instance = getInstance();
         checkNotNull(instance.billingTime, "Must set billing time");
         checkNotNull(instance.reason, "Must set reason");
-        checkState((instance.refOneTime == null) != (instance.refRecurring == null),
+        checkState(
+            (instance.refOneTime == null) != (instance.refRecurring == null),
             "Cancellations must have exactly one billing event key set");
         return super.build();
       }
     }
   }
-
-  /** An event representing a modification of an existing one-time billing event. */
-  @ReportedOn
-  @Entity
-  @WithLongVKey(compositeKey = true)
-  public static class Modification extends BillingEvent {
-
-    /** The change in cost that should be applied to the original billing event. */
-    Money cost;
-
-    /** The one-time billing event to modify. */
-    Key<BillingEvent.OneTime> eventRef;
-
-    /**
-     * Description of the modification (and presumably why it was issued). This text may appear as a
-     * line item on an invoice or report about such modifications.
-     */
-    String description;
-
-    public Money getCost() {
-      return cost;
-    }
-
-    public Key<BillingEvent.OneTime> getEventKey() {
-      return eventRef;
-    }
-
-    public String getDescription() {
-      return description;
-    }
-
-    @Override
-    public Builder asBuilder() {
-      return new Builder(clone(this));
-    }
-
-    @Override
-    public VKey<Modification> createVKey() {
-      return VKey.create(Modification.class, getId(), Key.create(this));
-    }
-
-    public static VKey<Modification> createVKey(Key<Modification> key) {
-      return VKey.create(Modification.class, key.getId(), key);
-    }
-
-    /**
-     * Create a new Modification billing event which is a refund of the given OneTime billing event
-     * and that is parented off the given HistoryEntry.
-     *
-     * <p>Note that this method may appear to be unused most of the time, but it is kept around
-     * because it is needed by one-off scrap tools that need to make billing adjustments.
-     */
-    public static Modification createRefundFor(
-        OneTime billingEvent, DomainHistory historyEntry, String description) {
-      return new Builder()
-          .setRegistrarId(billingEvent.getRegistrarId())
-          .setFlags(billingEvent.getFlags())
-          .setReason(billingEvent.getReason())
-          .setTargetId(billingEvent.getTargetId())
-          .setEventKey(Key.create(billingEvent))
-          .setEventTime(historyEntry.getModificationTime())
-          .setDescription(description)
-          .setCost(billingEvent.getCost().negated())
-          .setParent(historyEntry)
-          .build();
-    }
-
-    /** A builder for {@link Modification} since it is immutable. */
-    public static class Builder extends BillingEvent.Builder<Modification, Builder> {
-
-      public Builder() {}
-
-      private Builder(Modification instance) {
-        super(instance);
-      }
-
-      public Builder setCost(Money cost) {
-        getInstance().cost = cost;
-        return this;
-      }
-
-      public Builder setEventKey(Key<BillingEvent.OneTime> eventKey) {
-        getInstance().eventRef = eventKey;
-        return this;
-      }
-
-      public Builder setDescription(String description) {
-        getInstance().description = description;
-        return this;
-      }
-
-      @Override
-      public Modification build() {
-        Modification instance = getInstance();
-        checkNotNull(instance.reason);
-        checkNotNull(instance.eventRef);
-        BillingEvent.OneTime billingEvent =
-            tm().transact(() -> tm().loadByKey(VKey.from(instance.eventRef)));
-        checkArgument(
-            Objects.equals(instance.cost.getCurrencyUnit(), billingEvent.cost.getCurrencyUnit()),
-            "Referenced billing event is in a different currency");
-        return super.build();
-      }
-    }
-  }
 }

core/src/main/java/google/registry/model/bulkquery/BulkQueryEntities.java

@@ -19,8 +19,8 @@ import static com.google.common.collect.ImmutableSet.toImmutableSet;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainBase;
-import google.registry.model.domain.DomainContent;
 import google.registry.model.domain.DomainHistory;
 import google.registry.model.domain.GracePeriod;
 import google.registry.model.domain.GracePeriod.GracePeriodHistory;
@@ -33,14 +33,14 @@ import google.registry.persistence.transaction.JpaTransactionManager;
 
 /**
  * Utilities for managing an alternative JPA entity model optimized for bulk loading multi-level
- * entities such as {@link DomainBase} and {@link DomainHistory}.
+ * entities such as {@link Domain} and {@link DomainHistory}.
  *
  * <p>In a bulk query for a multi-level JPA entity type, the JPA framework only generates a bulk
  * query (SELECT * FROM table) for the base table. Then, for each row in the base table, additional
  * queries are issued to load associated rows in child tables. This can be very slow when an entity
  * type has multiple child tables.
  *
- * <p>We have defined an alternative entity model for {@code DomainBase} and {@code DomainHistory},
+ * <p>We have defined an alternative entity model for {@link Domain} and {@link DomainHistory},
  * where the base table as well as the child tables are mapped to single-level entity types. The
  * idea is to load each of these types using a bulk query, and assemble them into the target type in
  * memory in a pipeline. The main use case is Datastore-Cloud SQL validation during the Registry
@@ -53,8 +53,8 @@ public class BulkQueryEntities {
    */
   public static final ImmutableMap<String, String> JPA_ENTITIES_REPLACEMENTS =
       ImmutableMap.of(
-          DomainBase.class.getCanonicalName(),
-          DomainBaseLite.class.getCanonicalName(),
+          Domain.class.getCanonicalName(),
+          DomainLite.class.getCanonicalName(),
           DomainHistory.class.getCanonicalName(),
           DomainHistoryLite.class.getCanonicalName());
 
@@ -64,18 +64,18 @@ public class BulkQueryEntities {
       ImmutableList.of(
           DomainHost.class.getCanonicalName(), DomainHistoryHost.class.getCanonicalName());
 
-  public static DomainBase assembleDomainBase(
-      DomainBaseLite domainBaseLite,
+  public static Domain assembleDomain(
+      DomainLite domainLite,
       ImmutableSet<GracePeriod> gracePeriods,
       ImmutableSet<DelegationSignerData> delegationSignerData,
       ImmutableSet<VKey<HostResource>> nsHosts) {
-    DomainBase.Builder builder = new DomainBase.Builder();
-    builder.copyFrom(domainBaseLite);
+    Domain.Builder builder = new Domain.Builder();
+    builder.copyFrom(domainLite);
     builder.setGracePeriods(gracePeriods);
     builder.setDsData(delegationSignerData);
     builder.setNameservers(nsHosts);
     // Restore the original update timestamp (this gets cleared when we set nameservers or DS data).
-    builder.setUpdateTimestamp(domainBaseLite.getUpdateTimestamp());
+    builder.setUpdateTimestamp(domainLite.getUpdateTimestamp());
     return builder.build();
   }
 
@@ -87,11 +87,11 @@ public class BulkQueryEntities {
       ImmutableSet<DomainTransactionRecord> transactionRecords) {
     DomainHistory.Builder builder = new DomainHistory.Builder();
     builder.copyFrom(domainHistoryLite);
-    DomainContent rawDomainContent = domainHistoryLite.domainContent;
-    if (rawDomainContent != null) {
-      DomainContent newDomainContent =
+    DomainBase rawDomainBase = domainHistoryLite.domainBase;
+    if (rawDomainBase != null) {
+      DomainBase newDomainBase =
           domainHistoryLite
-              .domainContent
+              .domainBase
               .asBuilder()
               .setNameservers(domainHistoryHosts)
               .setGracePeriods(
@@ -104,9 +104,9 @@ public class BulkQueryEntities {
                       .collect(toImmutableSet()))
               // Restore the original update timestamp (this gets cleared when we set nameservers or
               // DS data).
-              .setUpdateTimestamp(domainHistoryLite.domainContent.getUpdateTimestamp())
+              .setUpdateTimestamp(domainHistoryLite.domainBase.getUpdateTimestamp())
               .build();
-      builder.setDomain(newDomainContent);
+      builder.setDomain(newDomainBase);
     }
     return builder.buildAndAssemble(
         dsDataHistories, domainHistoryHosts, gracePeriodHistories, transactionRecords);

core/src/main/java/google/registry/model/bulkquery/DomainHistoryLite.java

@@ -15,8 +15,8 @@
 package google.registry.model.bulkquery;
 
 import com.googlecode.objectify.Key;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainBase;
-import google.registry.model.domain.DomainContent;
 import google.registry.model.domain.DomainHistory;
 import google.registry.model.domain.DomainHistory.DomainHistoryId;
 import google.registry.model.domain.Period;
@@ -49,9 +49,9 @@ import javax.persistence.PostLoad;
 @IdClass(DomainHistoryId.class)
 public class DomainHistoryLite extends HistoryEntry {
 
-  // Store DomainContent instead of DomainBase so we don't pick up its @Id
+  // Store DomainBase instead of Domain so we don't pick up its @Id
   // Nullable for the sake of pre-Registry-3.0 history objects
-  @Nullable DomainContent domainContent;
+  @Nullable DomainBase domainBase;
 
   @Id
   @Access(AccessType.PROPERTY)
@@ -64,7 +64,7 @@ public class DomainHistoryLite extends HistoryEntry {
   /** This method is private because it is only used by Hibernate. */
   @SuppressWarnings("unused")
   private void setDomainRepoId(String domainRepoId) {
-    parent = Key.create(DomainBase.class, domainRepoId);
+    parent = Key.create(Domain.class, domainRepoId);
   }
 
   @Override
@@ -101,9 +101,9 @@ public class DomainHistoryLite extends HistoryEntry {
     return super.getId();
   }
 
-  /** The key to the {@link DomainBase} this is based off of. */
-  public VKey<DomainBase> getParentVKey() {
-    return VKey.create(DomainBase.class, getDomainRepoId());
+  /** The key to the {@link Domain} this is based off of. */
+  public VKey<Domain> getParentVKey() {
+    return VKey.create(Domain.class, getDomainRepoId());
   }
 
   public DomainHistoryId getDomainHistoryId() {
@@ -112,14 +112,14 @@ public class DomainHistoryLite extends HistoryEntry {
 
   @PostLoad
   void postLoad() {
-    if (domainContent == null) {
+    if (domainBase == null) {
       return;
     }
     // See inline comments in DomainHistory.postLoad for reasons for the following lines.
-    if (domainContent.getDomainName() == null) {
-      domainContent = null;
-    } else if (domainContent.getRepoId() == null) {
-      domainContent.setRepoId(parent.getName());
+    if (domainBase.getDomainName() == null) {
+      domainBase = null;
+    } else if (domainBase.getRepoId() == null) {
+      domainBase.setRepoId(parent.getName());
     }
   }
 }

core/src/main/java/google/registry/model/bulkquery/DomainLite.java

@@ -14,8 +14,8 @@
 
 package google.registry.model.bulkquery;
 
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainBase;
-import google.registry.model.domain.DomainContent;
 import google.registry.persistence.VKey;
 import google.registry.persistence.WithStringVKey;
 import javax.persistence.Access;
@@ -23,17 +23,17 @@ import javax.persistence.AccessType;
 import javax.persistence.Entity;
 
 /**
- * A 'light' version of {@link DomainBase} with only base table ("Domain") attributes, which allows
- * fast bulk loading. They are used in in-memory assembly of {@code DomainBase} instances along with
+ * A 'light' version of {@link Domain} with only base table ("Domain") attributes, which allows fast
+ * bulk loading. They are used in in-memory assembly of {@code Domain} instances along with
  * bulk-loaded child entities ({@code GracePeriod} etc). The in-memory assembly achieves much higher
- * performance than loading {@code DomainBase} directly.
+ * performance than loading {@code Domain} directly.
  *
  * <p>Please refer to {@link BulkQueryEntities} for more information.
  */
 @Entity(name = "Domain")
 @WithStringVKey
 @Access(AccessType.FIELD)
-public class DomainBaseLite extends DomainContent {
+public class DomainLite extends DomainBase {
 
   @Override
   @javax.persistence.Id
@@ -42,7 +42,7 @@ public class DomainBaseLite extends DomainContent {
     return super.getRepoId();
   }
 
-  public static VKey<DomainBaseLite> createVKey(String repoId) {
-    return VKey.createSql(DomainBaseLite.class, repoId);
+  public static VKey<DomainLite> createVKey(String repoId) {
+    return VKey.createSql(DomainLite.class, repoId);
   }
 }

core/src/main/java/google/registry/model/common/ClassPathManager.java

@@ -53,12 +53,16 @@ public class ClassPathManager {
   }
 
   public static <T> Class<T> getClass(String className) {
-    checkArgument(CLASS_REGISTRY.containsKey(className), "Class not found in class registry");
+    checkArgument(
+        CLASS_REGISTRY.containsKey(className), "Class %s not found in class registry", className);
     return (Class<T>) CLASS_REGISTRY.get(className);
   }
 
   public static <T> String getClassName(Class<T> clazz) {
-    checkArgument(CLASS_NAME_REGISTRY.containsKey(clazz), "Class not found in class name registry");
+    checkArgument(
+        CLASS_NAME_REGISTRY.containsKey(clazz),
+        "Class %s not found in class name registry",
+        clazz.getSimpleName());
     return CLASS_NAME_REGISTRY.get(clazz);
   }
 }

core/src/main/java/google/registry/model/common/DatabaseMigrationStateSchedule.java

@@ -197,7 +197,7 @@ public class DatabaseMigrationStateSchedule extends CrossTldSingleton {
             MigrationState.DATASTORE_ONLY,
             "migrationTransitionMap must start with DATASTORE_ONLY");
     validateTransitionAtCurrentTime(transitions);
-    jpaTm().putWithoutBackup(new DatabaseMigrationStateSchedule(transitions));
+    jpaTm().put(new DatabaseMigrationStateSchedule(transitions));
     CACHE.invalidateAll();
   }
 

core/src/main/java/google/registry/model/domain/Domain.java

@@ -0,0 +1,216 @@
+// Copyright 2017 The Nomulus Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package google.registry.model.domain;
+
+import com.googlecode.objectify.Key;
+import google.registry.model.EppResource;
+import google.registry.model.EppResource.ForeignKeyedEppResource;
+import google.registry.model.annotations.ExternalMessagingName;
+import google.registry.model.annotations.ReportedOn;
+import google.registry.model.domain.secdns.DelegationSignerData;
+import google.registry.model.host.HostResource;
+import google.registry.persistence.VKey;
+import google.registry.persistence.WithStringVKey;
+import java.util.Set;
+import javax.persistence.Access;
+import javax.persistence.AccessType;
+import javax.persistence.CascadeType;
+import javax.persistence.Column;
+import javax.persistence.ElementCollection;
+import javax.persistence.Entity;
+import javax.persistence.FetchType;
+import javax.persistence.Index;
+import javax.persistence.JoinColumn;
+import javax.persistence.JoinTable;
+import javax.persistence.OneToMany;
+import javax.persistence.PostLoad;
+import javax.persistence.Table;
+import org.hibernate.Hibernate;
+import org.joda.time.DateTime;
+
+/**
+ * A persistable domain resource including mutable and non-mutable fields.
+ *
+ * @see <a href="https://tools.ietf.org/html/rfc5731">RFC 5731</a>
+ */
+@ReportedOn
+@com.googlecode.objectify.annotation.Entity
+@Entity
+@Table(
+    name = "Domain",
+    indexes = {
+      @Index(columnList = "adminContact"),
+      @Index(columnList = "autorenewEndTime"),
+      @Index(columnList = "billingContact"),
+      @Index(columnList = "creationTime"),
+      @Index(columnList = "currentSponsorRegistrarId"),
+      @Index(columnList = "deletionTime"),
+      @Index(columnList = "domainName"),
+      @Index(columnList = "techContact"),
+      @Index(columnList = "tld"),
+      @Index(columnList = "registrantContact"),
+      @Index(columnList = "dnsRefreshRequestTime"),
+      @Index(columnList = "billing_recurrence_id"),
+      @Index(columnList = "transfer_billing_event_id"),
+      @Index(columnList = "transfer_billing_recurrence_id")
+    })
+@WithStringVKey
+@ExternalMessagingName("domain")
+@Access(AccessType.FIELD)
+public class Domain extends DomainBase implements ForeignKeyedEppResource {
+
+  @Override
+  @javax.persistence.Id
+  @Access(AccessType.PROPERTY)
+  public String getRepoId() {
+    return super.getRepoId();
+  }
+
+  // It seems like this should be FetchType.EAGER, but for some reason when we do that we get a lazy
+  // load error during the load of a domain.
+  @ElementCollection
+  @JoinTable(
+      name = "DomainHost",
+      indexes = {
+        @Index(columnList = "domain_repo_id,host_repo_id", unique = true),
+        @Index(columnList = "host_repo_id")
+      })
+  @Access(AccessType.PROPERTY)
+  @Column(name = "host_repo_id")
+  public Set<VKey<HostResource>> getNsHosts() {
+    return super.nsHosts;
+  }
+
+  /**
+   * Returns the set of {@link GracePeriod} associated with the domain.
+   *
+   * <p>This is the getter method specific for Hibernate to access the field so it is set to
+   * private. The caller can use the public {@link #getGracePeriods()} to get the grace periods.
+   *
+   * <p>Note that we need to set `insertable = false, updatable = false` for @JoinColumn, otherwise
+   * Hibernate would try to set the foreign key to null(through an UPDATE TABLE sql) instead of
+   * deleting the whole entry from the table when the {@link GracePeriod} is removed from the set.
+   */
+  @Access(AccessType.PROPERTY)
+  @OneToMany(
+      cascade = {CascadeType.ALL},
+      fetch = FetchType.EAGER,
+      orphanRemoval = true)
+  @JoinColumn(
+      name = "domainRepoId",
+      referencedColumnName = "repoId",
+      insertable = false,
+      updatable = false)
+  @SuppressWarnings("UnusedMethod")
+  private Set<GracePeriod> getInternalGracePeriods() {
+    return gracePeriods;
+  }
+
+  /**
+   * Returns the set of {@link DelegationSignerData} associated with the domain.
+   *
+   * <p>This is the getter method specific for Hibernate to access the field so it is set to
+   * private. The caller can use the public {@link #getDsData()} to get the DS data.
+   *
+   * <p>Note that we need to set `insertable = false, updatable = false` for @JoinColumn, otherwise
+   * Hibernate would try to set the foreign key to null(through an UPDATE TABLE sql) instead of
+   * deleting the whole entry from the table when the {@link DelegationSignerData} is removed from
+   * the set.
+   */
+  @Access(AccessType.PROPERTY)
+  @OneToMany(
+      cascade = {CascadeType.ALL},
+      fetch = FetchType.EAGER,
+      orphanRemoval = true)
+  @JoinColumn(
+      name = "domainRepoId",
+      referencedColumnName = "repoId",
+      insertable = false,
+      updatable = false)
+  @SuppressWarnings("UnusedMethod")
+  private Set<DelegationSignerData> getInternalDelegationSignerData() {
+    return dsData;
+  }
+
+  /** Post-load method to eager load the collections. */
+  @PostLoad
+  protected void postLoad() {
+    // TODO(b/188044616): Determine why Eager loading doesn't work here.
+    Hibernate.initialize(dsData);
+    Hibernate.initialize(gracePeriods);
+  }
+
+  @Override
+  public VKey<Domain> createVKey() {
+    return VKey.create(Domain.class, getRepoId(), Key.create(this));
+  }
+
+  @Override
+  public Domain cloneProjectedAtTime(final DateTime now) {
+    return cloneDomainProjectedAtTime(this, now);
+  }
+
+  public static VKey<Domain> createVKey(Key<Domain> key) {
+    return VKey.create(Domain.class, key.getName(), key);
+  }
+
+  /** An override of {@link EppResource#asBuilder} with tighter typing. */
+  @Override
+  public Builder asBuilder() {
+    return new Builder(clone(this));
+  }
+
+  /** A builder for constructing {@link Domain}, since it is immutable. */
+  public static class Builder extends DomainBase.Builder<Domain, Builder> {
+
+    public Builder() {}
+
+    Builder(Domain instance) {
+      super(instance);
+    }
+
+    public Builder copyFrom(DomainBase domainBase) {
+      this.getInstance().copyUpdateTimestamp(domainBase);
+      return this.setAuthInfo(domainBase.getAuthInfo())
+          .setAutorenewPollMessage(
+              domainBase.getAutorenewPollMessage(), domainBase.getAutorenewPollMessageHistoryId())
+          .setAutorenewBillingEvent(domainBase.getAutorenewBillingEvent())
+          .setAutorenewEndTime(domainBase.getAutorenewEndTime())
+          .setContacts(domainBase.getContacts())
+          .setCreationRegistrarId(domainBase.getCreationRegistrarId())
+          .setCreationTime(domainBase.getCreationTime())
+          .setDomainName(domainBase.getDomainName())
+          .setDeletePollMessage(domainBase.getDeletePollMessage())
+          .setDsData(domainBase.getDsData())
+          .setDeletionTime(domainBase.getDeletionTime())
+          .setGracePeriods(domainBase.getGracePeriods())
+          .setIdnTableName(domainBase.getIdnTableName())
+          .setLastTransferTime(domainBase.getLastTransferTime())
+          .setLaunchNotice(domainBase.getLaunchNotice())
+          .setLastEppUpdateRegistrarId(domainBase.getLastEppUpdateRegistrarId())
+          .setLastEppUpdateTime(domainBase.getLastEppUpdateTime())
+          .setNameservers(domainBase.getNameservers())
+          .setPersistedCurrentSponsorRegistrarId(domainBase.getPersistedCurrentSponsorRegistrarId())
+          .setRegistrant(domainBase.getRegistrant())
+          .setRegistrationExpirationTime(domainBase.getRegistrationExpirationTime())
+          .setRepoId(domainBase.getRepoId())
+          .setSmdId(domainBase.getSmdId())
+          .setSubordinateHosts(domainBase.getSubordinateHosts())
+          .setStatusValues(domainBase.getStatusValues())
+          .setTransferData(domainBase.getTransferData())
+          .setDnsRefreshRequestTime(domainBase.getDnsRefreshRequestTime());
+    }
+  }
+}

core/src/main/java/google/registry/model/domain/DomainCommand.java

@@ -54,7 +54,7 @@ import javax.xml.bind.annotation.XmlValue;
 import org.joda.time.DateTime;
 import org.joda.time.LocalDate;
 
-/** A collection of {@link DomainBase} commands. */
+/** A collection of {@link Domain} commands. */
 public class DomainCommand {
 
   /** The default validity period (if not specified) is 1 year for all operations. */
@@ -72,7 +72,7 @@ public class DomainCommand {
 
   /** The fields on "chgType" from <a href="http://tools.ietf.org/html/rfc5731">RFC5731</a>. */
   @XmlTransient
-  public static class DomainCreateOrChange<B extends DomainBase.Builder> extends ImmutableObject
+  public static class DomainCreateOrChange<B extends Domain.Builder> extends ImmutableObject
       implements ResourceCreateOrChange<B> {
 
     /** The contactId of the registrant who registered this domain. */
@@ -100,7 +100,7 @@ public class DomainCommand {
   }
 
   /**
-   * A create command for a {@link DomainBase}, mapping "createType" from <a
+   * A create command for a {@link Domain}, mapping "createType" from <a
    * href="http://tools.ietf.org/html/rfc5731">RFC5731</a>.
    */
   @XmlRootElement
@@ -113,7 +113,7 @@ public class DomainCommand {
         "foreignKeyedDesignatedContacts",
         "authInfo"
       })
-  public static class Create extends DomainCreateOrChange<DomainBase.Builder>
+  public static class Create extends DomainCreateOrChange<Domain.Builder>
       implements CreateOrUpdate<Create> {
 
     /** Fully qualified domain name, which serves as a unique identifier for this domain. */
@@ -196,11 +196,11 @@ public class DomainCommand {
     }
   }
 
-  /** A delete command for a {@link DomainBase}. */
+  /** A delete command for a {@link Domain}. */
   @XmlRootElement
   public static class Delete extends AbstractSingleResourceCommand {}
 
-  /** An info request for a {@link DomainBase}. */
+  /** An info request for a {@link Domain}. */
   @XmlRootElement
   public static class Info extends ImmutableObject implements SingleResourceCommand {
 
@@ -259,11 +259,11 @@ public class DomainCommand {
     }
   }
 
-  /** A check request for {@link DomainBase}. */
+  /** A check request for {@link Domain}. */
   @XmlRootElement
   public static class Check extends ResourceCheck {}
 
-  /** A renew command for a {@link DomainBase}. */
+  /** A renew command for a {@link Domain}. */
   @XmlRootElement
   public static class Renew extends AbstractSingleResourceCommand {
     @XmlElement(name = "curExpDate")
@@ -281,7 +281,7 @@ public class DomainCommand {
     }
   }
 
-  /** A transfer operation for a {@link DomainBase}. */
+  /** A transfer operation for a {@link Domain}. */
   @XmlRootElement
   public static class Transfer extends AbstractSingleResourceCommand {
     /** The period to extend this domain's registration upon completion of the transfer. */
@@ -300,11 +300,10 @@ public class DomainCommand {
     }
   }
 
-  /** An update to a {@link DomainBase}. */
+  /** An update to a {@link Domain}. */
   @XmlRootElement
   @XmlType(propOrder = {"targetId", "innerAdd", "innerRemove", "innerChange"})
-  public static class Update
-      extends ResourceUpdate<Update.AddRemove, DomainBase.Builder, Update.Change>
+  public static class Update extends ResourceUpdate<Update.AddRemove, Domain.Builder, Update.Change>
       implements CreateOrUpdate<Update> {
 
     @XmlElement(name = "chg")
@@ -383,7 +382,7 @@ public class DomainCommand {
 
     /** The inner change type on a domain update command. */
     @XmlType(propOrder = {"registrantContactId", "authInfo"})
-    public static class Change extends DomainCreateOrChange<DomainBase.Builder> {
+    public static class Change extends DomainCreateOrChange<Domain.Builder> {
       /** Creates a copy of this {@link Change} with hard links to hosts and contacts. */
       Change cloneAndLinkReferences(DateTime now) throws InvalidReferencesException {
         Change clone = clone(this);

core/src/main/java/google/registry/model/domain/DomainContent.java

@@ -1,947 +0,0 @@
-// Copyright 2017 The Nomulus Authors. All Rights Reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package google.registry.model.domain;
-
-import static com.google.common.base.MoreObjects.firstNonNull;
-import static com.google.common.base.Preconditions.checkArgument;
-import static com.google.common.base.Strings.emptyToNull;
-import static com.google.common.collect.ImmutableSet.toImmutableSet;
-import static com.google.common.collect.ImmutableSortedSet.toImmutableSortedSet;
-import static com.google.common.collect.Sets.difference;
-import static com.google.common.collect.Sets.intersection;
-import static google.registry.model.EppResourceUtils.projectResourceOntoBuilderAtTime;
-import static google.registry.model.EppResourceUtils.setAutomaticTransferSuccessProperties;
-import static google.registry.persistence.transaction.TransactionManagerFactory.tm;
-import static google.registry.util.CollectionUtils.forceEmptyToNull;
-import static google.registry.util.CollectionUtils.nullToEmpty;
-import static google.registry.util.CollectionUtils.nullToEmptyImmutableCopy;
-import static google.registry.util.CollectionUtils.union;
-import static google.registry.util.DateTimeUtils.END_OF_TIME;
-import static google.registry.util.DateTimeUtils.earliestOf;
-import static google.registry.util.DateTimeUtils.isBeforeOrAt;
-import static google.registry.util.DateTimeUtils.leapSafeAddYears;
-import static google.registry.util.DomainNameUtils.canonicalizeHostname;
-import static google.registry.util.DomainNameUtils.getTldFromDomainName;
-import static google.registry.util.PreconditionsUtils.checkArgumentNotNull;
-
-import com.google.common.base.Predicate;
-import com.google.common.collect.ImmutableSet;
-import com.google.common.collect.ImmutableSortedSet;
-import com.google.common.collect.Ordering;
-import com.google.common.collect.Sets;
-import com.googlecode.objectify.Key;
-import com.googlecode.objectify.annotation.Ignore;
-import com.googlecode.objectify.annotation.IgnoreSave;
-import com.googlecode.objectify.annotation.Index;
-import com.googlecode.objectify.condition.IfNull;
-import google.registry.dns.RefreshDnsAction;
-import google.registry.flows.ResourceFlowUtils;
-import google.registry.model.EppResource;
-import google.registry.model.EppResource.ResourceWithTransferData;
-import google.registry.model.billing.BillingEvent;
-import google.registry.model.common.EntityGroupRoot;
-import google.registry.model.contact.ContactResource;
-import google.registry.model.domain.launch.LaunchNotice;
-import google.registry.model.domain.rgp.GracePeriodStatus;
-import google.registry.model.domain.secdns.DelegationSignerData;
-import google.registry.model.eppcommon.StatusValue;
-import google.registry.model.host.HostResource;
-import google.registry.model.poll.PollMessage;
-import google.registry.model.reporting.HistoryEntry;
-import google.registry.model.tld.Registry;
-import google.registry.model.transfer.DomainTransferData;
-import google.registry.model.transfer.TransferStatus;
-import google.registry.persistence.VKey;
-import google.registry.util.CollectionUtils;
-import google.registry.util.DateTimeUtils;
-import java.util.HashSet;
-import java.util.Objects;
-import java.util.Optional;
-import java.util.Set;
-import javax.annotation.Nullable;
-import javax.persistence.Access;
-import javax.persistence.AccessType;
-import javax.persistence.AttributeOverride;
-import javax.persistence.AttributeOverrides;
-import javax.persistence.Column;
-import javax.persistence.Embeddable;
-import javax.persistence.Embedded;
-import javax.persistence.MappedSuperclass;
-import javax.persistence.Transient;
-import org.hibernate.collection.internal.PersistentSet;
-import org.joda.time.DateTime;
-import org.joda.time.Interval;
-
-/**
- * A persistable domain resource including mutable and non-mutable fields.
- *
- * <p>This class deliberately does not include an {@link javax.persistence.Id} so that any
- * foreign-keyed fields can refer to the proper parent entity's ID, whether we're storing this in
- * the DB itself or as part of another entity.
- *
- * <p>For historical reasons, the name of this class is "DomainContent". Ideally it would be
- * "DomainBase" for parallelism with the other {@link EppResource} entity classes, but because that
- * name is already taken by {@link DomainBase} (also for historical reasons), we can't use it. Once
- * we are no longer on Datastore, we can rename the classes.
- *
- * @see <a href="https://tools.ietf.org/html/rfc5731">RFC 5731</a>
- */
-@MappedSuperclass
-@Embeddable
-@Access(AccessType.FIELD)
-public class DomainContent extends EppResource
-    implements ResourceWithTransferData<DomainTransferData> {
-
-  /** The max number of years that a domain can be registered for, as set by ICANN policy. */
-  public static final int MAX_REGISTRATION_YEARS = 10;
-
-  /** Status values which prohibit DNS information from being published. */
-  private static final ImmutableSet<StatusValue> DNS_PUBLISHING_PROHIBITED_STATUSES =
-      ImmutableSet.of(
-          StatusValue.CLIENT_HOLD,
-          StatusValue.INACTIVE,
-          StatusValue.PENDING_DELETE,
-          StatusValue.SERVER_HOLD);
-
-  /**
-   * Fully qualified domain name (puny-coded), which serves as the foreign key for this domain.
-   *
-   * <p>This is only unique in the sense that for any given lifetime specified as the time range
-   * from (creationTime, deletionTime) there can only be one domain in Datastore with this name.
-   * However, there can be many domains with the same name and non-overlapping lifetimes.
-   *
-   * @invariant fullyQualifiedDomainName == fullyQualifiedDomainName.toLowerCase(Locale.ENGLISH)
-   */
-  // TODO(b/177567432): Rename this to domainName when we are off Datastore
-  @Column(name = "domainName")
-  @Index
-  String fullyQualifiedDomainName;
-
-  /** The top level domain this is under, dernormalized from {@link #fullyQualifiedDomainName}. */
-  @Index String tld;
-
-  /** References to hosts that are the nameservers for the domain. */
-  @EmptySetToNull @Index @Transient Set<VKey<HostResource>> nsHosts;
-
-  /** Contacts. */
-  VKey<ContactResource> adminContact;
-
-  VKey<ContactResource> billingContact;
-  VKey<ContactResource> techContact;
-  VKey<ContactResource> registrantContact;
-
-  /** Authorization info (aka transfer secret) of the domain. */
-  @Embedded
-  @AttributeOverrides({
-    @AttributeOverride(name = "pw.value", column = @Column(name = "auth_info_value")),
-    @AttributeOverride(name = "pw.repoId", column = @Column(name = "auth_info_repo_id")),
-  })
-  DomainAuthInfo authInfo;
-
-  /** Data used to construct DS records for this domain. */
-  @Transient Set<DelegationSignerData> dsData;
-
-  /**
-   * The claims notice supplied when this domain was created, if there was one.
-   *
-   * <p>It's {@literal @}XmlTransient because it's not returned in an info response.
-   */
-  @Embedded
-  @AttributeOverrides({
-    @AttributeOverride(name = "noticeId.tcnId", column = @Column(name = "launch_notice_tcn_id")),
-    @AttributeOverride(
-        name = "noticeId.validatorId",
-        column = @Column(name = "launch_notice_validator_id")),
-    @AttributeOverride(
-        name = "expirationTime",
-        column = @Column(name = "launch_notice_expiration_time")),
-    @AttributeOverride(
-        name = "acceptedTime",
-        column = @Column(name = "launch_notice_accepted_time")),
-  })
-  LaunchNotice launchNotice;
-
-  /**
-   * Name of first IDN table associated with TLD that matched the characters in this domain label.
-   *
-   * @see google.registry.tldconfig.idn.IdnLabelValidator#findValidIdnTableForTld
-   */
-  @IgnoreSave(IfNull.class)
-  String idnTableName;
-
-  /** Fully qualified host names of this domain's active subordinate hosts. */
-  Set<String> subordinateHosts;
-
-  /** When this domain's registration will expire. */
-  DateTime registrationExpirationTime;
-
-  /**
-   * The poll message associated with this domain being deleted.
-   *
-   * <p>This field should be null if the domain is not in pending delete. If it is, the field should
-   * refer to a {@link PollMessage} timed to when the domain is fully deleted. If the domain is
-   * restored, the message should be deleted.
-   */
-  @Column(name = "deletion_poll_message_id")
-  VKey<PollMessage.OneTime> deletePollMessage;
-
-  /**
-   * The recurring billing event associated with this domain's autorenewals.
-   *
-   * <p>The recurrence should be open ended unless the domain is in pending delete or fully deleted,
-   * in which case it should be closed at the time the delete was requested. Whenever the domain's
-   * {@link #registrationExpirationTime} is changed the recurrence should be closed, a new one
-   * should be created, and this field should be updated to point to the new one.
-   */
-  @Column(name = "billing_recurrence_id")
-  VKey<BillingEvent.Recurring> autorenewBillingEvent;
-
-  /**
-   * The recurring poll message associated with this domain's autorenewals.
-   *
-   * <p>The recurrence should be open ended unless the domain is in pending delete or fully deleted,
-   * in which case it should be closed at the time the delete was requested. Whenever the domain's
-   * {@link #registrationExpirationTime} is changed the recurrence should be closed, a new one
-   * should be created, and this field should be updated to point to the new one.
-   */
-  @Column(name = "autorenew_poll_message_id")
-  VKey<PollMessage.Autorenew> autorenewPollMessage;
-
-  /**
-   * History record for the autorenew poll message.
-   *
-   * <p>Here so we can restore the original ofy key from sql.
-   */
-  @Ignore Long autorenewPollMessageHistoryId;
-
-  /** The unexpired grace periods for this domain (some of which may not be active yet). */
-  @Transient Set<GracePeriod> gracePeriods;
-
-  /**
-   * The id of the signed mark that was used to create this domain in sunrise.
-   *
-   * <p>Will only be populated for domains created in sunrise.
-   */
-  @IgnoreSave(IfNull.class)
-  String smdId;
-
-  /** Data about any pending or past transfers on this domain. */
-  DomainTransferData transferData;
-
-  /**
-   * The time that this resource was last transferred.
-   *
-   * <p>Can be null if the resource has never been transferred.
-   */
-  DateTime lastTransferTime;
-
-  /**
-   * When the domain's autorenewal status will expire.
-   *
-   * <p>This will be {@link DateTimeUtils#END_OF_TIME} for the vast majority of domains because all
-   * domains autorenew indefinitely by default and autorenew can only be countermanded by
-   * administrators, typically for reasons of the URS process or termination of a registrar for
-   * nonpayment.
-   *
-   * <p>When a domain is scheduled to not autorenew, this field is set to the current value of its
-   * {@link #registrationExpirationTime}, after which point the next invocation of a periodic
-   * cronjob will explicitly delete the domain. This field is a DateTime and not a boolean because
-   * of edge cases that occur during the autorenew grace period. We need to be able to tell the
-   * difference domains that have reached their life and must be deleted now, and domains that
-   * happen to be in the autorenew grace period now but should be deleted in roughly a year.
-   */
-  @Index DateTime autorenewEndTime;
-
-  /**
-   * When this domain's DNS was requested to be refreshed, or null if its DNS is up-to-date.
-   *
-   * <p>This will almost always be null except in the couple minutes' interval between when a
-   * DNS-affecting create or update operation takes place and when the {@link RefreshDnsAction}
-   * runs, which resets this back to null upon completion of the DNS refresh task. This is a {@link
-   * DateTime} rather than a simple dirty boolean so that the DNS refresh action can order by the
-   * DNS refresh request time and take action on the oldest ones first.
-   *
-   * <p>Note that this is a Cloud SQL-based replacement for the {@code dns-pull} task queue. The
-   * domains that have a non-null value for this field should be exactly the same as the tasks that
-   * would be in the {@code dns-pull} queue. Because this is Cloud SQL-specific, it is omitted from
-   * Datastore.
-   *
-   * <p>Note that in the {@link DomainHistory} table this value means something slightly different:
-   * It means that the given domain action requested a DNS update. Unlike on the {@code Domain}
-   * table, this value is not then subsequently nulled out once the DNS refresh is complete; rather,
-   * it remains as a permanent record of which actions were DNS-affecting and which were not.
-   */
-  // TODO(mcilwain): Start using this field once we are further along in the DB migration.
-  @Ignore DateTime dnsRefreshRequestTime;
-
-  /**
-   * Returns the DNS refresh request time iff this domain's DNS needs refreshing, otherwise absent.
-   */
-  public Optional<DateTime> getDnsRefreshRequestTime() {
-    return Optional.ofNullable(dnsRefreshRequestTime);
-  }
-
-  public static <T> VKey<T> restoreOfyFrom(Key<DomainBase> domainKey, VKey<T> key, Long historyId) {
-    if (historyId == null) {
-      // This is a legacy key (or a null key, in which case this works too)
-      return VKey.restoreOfyFrom(key, EntityGroupRoot.class, "per-tld");
-    } else {
-      return VKey.restoreOfyFrom(key, domainKey, HistoryEntry.class, historyId);
-    }
-  }
-
-  public ImmutableSet<String> getSubordinateHosts() {
-    return nullToEmptyImmutableCopy(subordinateHosts);
-  }
-
-  public DateTime getRegistrationExpirationTime() {
-    return registrationExpirationTime;
-  }
-
-  public VKey<PollMessage.OneTime> getDeletePollMessage() {
-    return deletePollMessage;
-  }
-
-  public VKey<BillingEvent.Recurring> getAutorenewBillingEvent() {
-    return autorenewBillingEvent;
-  }
-
-  public VKey<PollMessage.Autorenew> getAutorenewPollMessage() {
-    return autorenewPollMessage;
-  }
-
-  public Long getAutorenewPollMessageHistoryId() {
-    return autorenewPollMessageHistoryId;
-  }
-
-  public ImmutableSet<GracePeriod> getGracePeriods() {
-    return nullToEmptyImmutableCopy(gracePeriods);
-  }
-
-  public String getSmdId() {
-    return smdId;
-  }
-
-  /**
-   * Returns the autorenew end time if there is one, otherwise empty.
-   *
-   * <p>Note that {@link DateTimeUtils#END_OF_TIME} is used as a sentinel value in the database
-   * representation to signify that autorenew doesn't end, and is mapped to empty here for the
-   * purposes of more legible business logic.
-   */
-  public Optional<DateTime> getAutorenewEndTime() {
-    return Optional.ofNullable(autorenewEndTime.equals(END_OF_TIME) ? null : autorenewEndTime);
-  }
-
-  @Override
-  public DomainTransferData getTransferData() {
-    return Optional.ofNullable(transferData).orElse(DomainTransferData.EMPTY);
-  }
-
-  @Override
-  public DateTime getLastTransferTime() {
-    return lastTransferTime;
-  }
-
-  @Override
-  public String getForeignKey() {
-    return fullyQualifiedDomainName;
-  }
-
-  public String getDomainName() {
-    return fullyQualifiedDomainName;
-  }
-
-  public ImmutableSet<DelegationSignerData> getDsData() {
-    return nullToEmptyImmutableCopy(dsData);
-  }
-
-  public LaunchNotice getLaunchNotice() {
-    return launchNotice;
-  }
-
-  public String getIdnTableName() {
-    return idnTableName;
-  }
-
-  public ImmutableSet<VKey<HostResource>> getNameservers() {
-    return nullToEmptyImmutableCopy(nsHosts);
-  }
-
-  // Hibernate needs this in order to populate nsHosts but no one else should ever use it
-  @SuppressWarnings("UnusedMethod")
-  private void setNsHosts(Set<VKey<HostResource>> nsHosts) {
-    this.nsHosts = forceEmptyToNull(nsHosts);
-  }
-
-  // Note: for the two methods below, how we wish to treat the Hibernate setters depends on the
-  // current state of the object and what's passed in. The key principle is that we wish to maintain
-  // the link between parent and child objects, meaning that we should keep around whichever of the
-  // two sets (the parameter vs the class variable and clear/populate that as appropriate.
-  //
-  // If the class variable is a PersistentSet and we overwrite it here, Hibernate will throw
-  // an exception "A collection with cascade=”all-delete-orphan” was no longer referenced by the
-  // owning entity instance". See https://stackoverflow.com/questions/5587482 for more details.
-
-  // Hibernate needs this in order to populate gracePeriods but no one else should ever use it
-  @SuppressWarnings("UnusedMethod")
-  private void setInternalGracePeriods(Set<GracePeriod> gracePeriods) {
-    if (this.gracePeriods instanceof PersistentSet) {
-      Set<GracePeriod> nonNullGracePeriods = nullToEmpty(gracePeriods);
-      this.gracePeriods.retainAll(nonNullGracePeriods);
-      this.gracePeriods.addAll(nonNullGracePeriods);
-    } else {
-      this.gracePeriods = gracePeriods;
-    }
-  }
-
-  // Hibernate needs this in order to populate dsData but no one else should ever use it
-  @SuppressWarnings("UnusedMethod")
-  private void setInternalDelegationSignerData(Set<DelegationSignerData> dsData) {
-    if (this.dsData instanceof PersistentSet) {
-      Set<DelegationSignerData> nonNullDsData = nullToEmpty(dsData);
-      this.dsData.retainAll(nonNullDsData);
-      this.dsData.addAll(nonNullDsData);
-    } else {
-      this.dsData = dsData;
-    }
-  }
-
-  public final String getCurrentSponsorRegistrarId() {
-    return getPersistedCurrentSponsorRegistrarId();
-  }
-
-  /** Returns true if DNS information should be published for the given domain. */
-  public boolean shouldPublishToDns() {
-    return intersection(getStatusValues(), DNS_PUBLISHING_PROHIBITED_STATUSES).isEmpty();
-  }
-
-  /**
-   * Returns the Registry Grace Period Statuses for this domain.
-   *
-   * <p>This collects all statuses from the domain's {@link GracePeriod} entries and also adds the
-   * PENDING_DELETE status if needed.
-   */
-  public ImmutableSet<GracePeriodStatus> getGracePeriodStatuses() {
-    Set<GracePeriodStatus> gracePeriodStatuses = new HashSet<>();
-    for (GracePeriod gracePeriod : getGracePeriods()) {
-      gracePeriodStatuses.add(gracePeriod.getType());
-    }
-    if (getStatusValues().contains(StatusValue.PENDING_DELETE)
-        && !gracePeriodStatuses.contains(GracePeriodStatus.REDEMPTION)) {
-      gracePeriodStatuses.add(GracePeriodStatus.PENDING_DELETE);
-    }
-    return ImmutableSet.copyOf(gracePeriodStatuses);
-  }
-
-  /** Returns the subset of grace periods having the specified type. */
-  public ImmutableSet<GracePeriod> getGracePeriodsOfType(GracePeriodStatus gracePeriodType) {
-    ImmutableSet.Builder<GracePeriod> builder = new ImmutableSet.Builder<>();
-    for (GracePeriod gracePeriod : getGracePeriods()) {
-      if (gracePeriod.getType() == gracePeriodType) {
-        builder.add(gracePeriod);
-      }
-    }
-    return builder.build();
-  }
-
-  @Override
-  public DomainContent cloneProjectedAtTime(final DateTime now) {
-    return cloneDomainProjectedAtTime(this, now);
-  }
-
-  /**
-   * The logic in this method, which handles implicit server approval of transfers, very closely
-   * parallels the logic in {@code DomainTransferApproveFlow} which handles explicit client
-   * approvals.
-   */
-  static <T extends DomainContent> T cloneDomainProjectedAtTime(T domain, DateTime now) {
-    DomainTransferData transferData = domain.getTransferData();
-    DateTime transferExpirationTime = transferData.getPendingTransferExpirationTime();
-
-    // If there's a pending transfer that has expired, handle it.
-    if (TransferStatus.PENDING.equals(transferData.getTransferStatus())
-        && isBeforeOrAt(transferExpirationTime, now)) {
-      // Project until just before the transfer time. This will handle the case of an autorenew
-      // before the transfer was even requested or during the request period.
-      // If the transfer time is precisely the moment that the domain expires, there will not be an
-      // autorenew billing event (since we end the recurrence at transfer time and recurrences are
-      // exclusive of their ending), and we can just proceed with the transfer.
-      T domainAtTransferTime =
-          cloneDomainProjectedAtTime(domain, transferExpirationTime.minusMillis(1));
-
-      DateTime expirationDate = transferData.getTransferredRegistrationExpirationTime();
-      if (expirationDate == null) {
-        // Extend the registration by the correct number of years from the expiration time
-        // that was current on the domain right before the transfer, capped at 10 years from
-        // the moment of the transfer.
-        expirationDate =
-            ResourceFlowUtils.computeExDateForApprovalTime(
-                domainAtTransferTime, transferExpirationTime, transferData.getTransferPeriod());
-      }
-      // If we are within an autorenew grace period, the transfer will subsume the autorenew. There
-      // will already be a cancellation written in advance by the transfer request flow, so we don't
-      // need to worry about billing, but we do need to cancel out the expiration time increase.
-      // The transfer period saved in the transfer data will be one year, unless the superuser
-      // extension set the transfer period to zero.
-      // Set the expiration, autorenew events, and grace period for the transfer. (Transfer ends
-      // all other graces).
-      Builder builder =
-          domainAtTransferTime
-              .asBuilder()
-              .setRegistrationExpirationTime(expirationDate)
-              // Set the speculatively-written new autorenew events as the domain's autorenew
-              // events.
-              .setAutorenewBillingEvent(transferData.getServerApproveAutorenewEvent())
-              .setAutorenewPollMessage(
-                  transferData.getServerApproveAutorenewPollMessage(),
-                  transferData.getServerApproveAutorenewPollMessageHistoryId());
-      if (transferData.getTransferPeriod().getValue() == 1) {
-        // Set the grace period using a key to the prescheduled transfer billing event.  Not using
-        // GracePeriod.forBillingEvent() here in order to avoid the actual Datastore fetch.
-        builder.setGracePeriods(
-            ImmutableSet.of(
-                GracePeriod.create(
-                    GracePeriodStatus.TRANSFER,
-                    domain.getRepoId(),
-                    transferExpirationTime.plus(
-                        Registry.get(domain.getTld()).getTransferGracePeriodLength()),
-                    transferData.getGainingRegistrarId(),
-                    transferData.getServerApproveBillingEvent())));
-      } else {
-        // There won't be a billing event, so we don't need a grace period
-        builder.setGracePeriods(ImmutableSet.of());
-      }
-      // Set all remaining transfer properties.
-      setAutomaticTransferSuccessProperties(builder, transferData);
-      builder
-          .setLastEppUpdateTime(transferExpirationTime)
-          .setLastEppUpdateRegistrarId(transferData.getGainingRegistrarId());
-      // Finish projecting to now.
-      return (T) builder.build().cloneProjectedAtTime(now);
-    }
-
-    Optional<DateTime> newLastEppUpdateTime = Optional.empty();
-
-    // There is no transfer. Do any necessary autorenews for active domains.
-
-    Builder builder = domain.asBuilder();
-    if (isBeforeOrAt(domain.getRegistrationExpirationTime(), now)
-        && END_OF_TIME.equals(domain.getDeletionTime())) {
-      // Autorenew by the number of years between the old expiration time and now.
-      DateTime lastAutorenewTime =
-          leapSafeAddYears(
-              domain.getRegistrationExpirationTime(),
-              new Interval(domain.getRegistrationExpirationTime(), now).toPeriod().getYears());
-      DateTime newExpirationTime = lastAutorenewTime.plusYears(1);
-      builder
-          .setRegistrationExpirationTime(newExpirationTime)
-          .addGracePeriod(
-              GracePeriod.createForRecurring(
-                  GracePeriodStatus.AUTO_RENEW,
-                  domain.getRepoId(),
-                  lastAutorenewTime.plus(
-                      Registry.get(domain.getTld()).getAutoRenewGracePeriodLength()),
-                  domain.getCurrentSponsorRegistrarId(),
-                  domain.getAutorenewBillingEvent()));
-      newLastEppUpdateTime = Optional.of(lastAutorenewTime);
-    }
-
-    // Remove any grace periods that have expired.
-    T almostBuilt = (T) builder.build();
-    builder = almostBuilt.asBuilder();
-    for (GracePeriod gracePeriod : almostBuilt.getGracePeriods()) {
-      if (isBeforeOrAt(gracePeriod.getExpirationTime(), now)) {
-        builder.removeGracePeriod(gracePeriod);
-        if (!newLastEppUpdateTime.isPresent()
-            || isBeforeOrAt(newLastEppUpdateTime.get(), gracePeriod.getExpirationTime())) {
-          newLastEppUpdateTime = Optional.of(gracePeriod.getExpirationTime());
-        }
-      }
-    }
-
-    // It is possible that the lastEppUpdateClientId is different from current sponsor client
-    // id, so we have to do the comparison instead of having one variable just storing the most
-    // recent time.
-    if (newLastEppUpdateTime.isPresent()) {
-      if (domain.getLastEppUpdateTime() == null
-          || newLastEppUpdateTime.get().isAfter(domain.getLastEppUpdateTime())) {
-        builder
-            .setLastEppUpdateTime(newLastEppUpdateTime.get())
-            .setLastEppUpdateRegistrarId(domain.getCurrentSponsorRegistrarId());
-      }
-    }
-
-    // Handle common properties like setting or unsetting linked status. This also handles the
-    // general case of pending transfers for other resource types, but since we've always handled
-    // a pending transfer by this point that's a no-op for domains.
-    projectResourceOntoBuilderAtTime(almostBuilt, builder, now);
-    return (T) builder.build();
-  }
-
-  /** Return what the expiration time would be if the given number of years were added to it. */
-  public static DateTime extendRegistrationWithCap(
-      DateTime now, DateTime currentExpirationTime, @Nullable Integer extendedRegistrationYears) {
-    // We must cap registration at the max years (aka 10), even if that truncates the last year.
-    return earliestOf(
-        leapSafeAddYears(
-            currentExpirationTime, Optional.ofNullable(extendedRegistrationYears).orElse(0)),
-        leapSafeAddYears(now, MAX_REGISTRATION_YEARS));
-  }
-
-  /** Loads and returns the fully qualified host names of all linked nameservers. */
-  public ImmutableSortedSet<String> loadNameserverHostNames() {
-    return tm().transact(
-            () ->
-                tm().loadByKeys(getNameservers()).values().stream()
-                    .map(HostResource::getHostName)
-                    .collect(toImmutableSortedSet(Ordering.natural())));
-  }
-
-  /** A key to the registrant who registered this domain. */
-  public VKey<ContactResource> getRegistrant() {
-    return registrantContact;
-  }
-
-  public VKey<ContactResource> getAdminContact() {
-    return adminContact;
-  }
-
-  public VKey<ContactResource> getBillingContact() {
-    return billingContact;
-  }
-
-  public VKey<ContactResource> getTechContact() {
-    return techContact;
-  }
-
-  /** Associated contacts for the domain (other than registrant). */
-  public ImmutableSet<DesignatedContact> getContacts() {
-    return getAllContacts(false);
-  }
-
-  public DomainAuthInfo getAuthInfo() {
-    return authInfo;
-  }
-
-  /** Returns all referenced contacts from this domain. */
-  public ImmutableSet<VKey<ContactResource>> getReferencedContacts() {
-    return nullToEmptyImmutableCopy(getAllContacts(true)).stream()
-        .map(DesignatedContact::getContactKey)
-        .filter(Objects::nonNull)
-        .collect(toImmutableSet());
-  }
-
-  private ImmutableSet<DesignatedContact> getAllContacts(boolean includeRegistrant) {
-    ImmutableSet.Builder<DesignatedContact> builder = new ImmutableSet.Builder<>();
-    if (includeRegistrant && registrantContact != null) {
-      builder.add(DesignatedContact.create(DesignatedContact.Type.REGISTRANT, registrantContact));
-    }
-    if (adminContact != null) {
-      builder.add(DesignatedContact.create(DesignatedContact.Type.ADMIN, adminContact));
-    }
-    if (billingContact != null) {
-      builder.add(DesignatedContact.create(DesignatedContact.Type.BILLING, billingContact));
-    }
-    if (techContact != null) {
-      builder.add(DesignatedContact.create(DesignatedContact.Type.TECH, techContact));
-    }
-    return builder.build();
-  }
-
-  public String getTld() {
-    return tld;
-  }
-
-  /**
-   * Sets the individual contact fields from {@code contacts}.
-   *
-   * <p>The registrant field is only set if {@code includeRegistrant} is true, as this field needs
-   * to be set in some circumstances but not in others.
-   */
-  void setContactFields(Set<DesignatedContact> contacts, boolean includeRegistrant) {
-    // Set the individual contact fields.
-    billingContact = techContact = adminContact = null;
-    if (includeRegistrant) {
-      registrantContact = null;
-    }
-    HashSet<DesignatedContact.Type> contactsDiscovered = new HashSet<DesignatedContact.Type>();
-    for (DesignatedContact contact : contacts) {
-      checkArgument(
-          !contactsDiscovered.contains(contact.getType()),
-          "Duplicate contact type %s in designated contact set.",
-          contact.getType());
-      contactsDiscovered.add(contact.getType());
-      switch (contact.getType()) {
-        case BILLING:
-          billingContact = contact.getContactKey();
-          break;
-        case TECH:
-          techContact = contact.getContactKey();
-          break;
-        case ADMIN:
-          adminContact = contact.getContactKey();
-          break;
-        case REGISTRANT:
-          if (includeRegistrant) {
-            registrantContact = contact.getContactKey();
-          }
-          break;
-        default:
-          throw new IllegalArgumentException("Unknown contact resource type: " + contact.getType());
-      }
-    }
-  }
-
-  @Override
-  public VKey<DomainBase> createVKey() {
-    throw new UnsupportedOperationException(
-        "DomainContent is not an actual persisted entity you can create a key to;"
-            + " use DomainBase instead");
-  }
-
-  /** Predicate to determine if a given {@link DesignatedContact} is the registrant. */
-  static final Predicate<DesignatedContact> IS_REGISTRANT =
-      (DesignatedContact contact) -> DesignatedContact.Type.REGISTRANT.equals(contact.type);
-
-  /** An override of {@link EppResource#asBuilder} with tighter typing. */
-  @Override
-  public Builder<? extends DomainContent, ?> asBuilder() {
-    return new Builder<>(clone(this));
-  }
-
-  /** A builder for constructing {@link DomainBase}, since it is immutable. */
-  public static class Builder<T extends DomainContent, B extends Builder<T, B>>
-      extends EppResource.Builder<T, B> implements BuilderWithTransferData<DomainTransferData, B> {
-
-    public Builder() {}
-
-    Builder(T instance) {
-      super(instance);
-    }
-
-    @Override
-    public T build() {
-      T instance = getInstance();
-      // If TransferData is totally empty, set it to null.
-      if (DomainTransferData.EMPTY.equals(getInstance().transferData)) {
-        setTransferData(null);
-      }
-      // A DomainBase has status INACTIVE if there are no nameservers.
-      if (getInstance().getNameservers().isEmpty()) {
-        addStatusValue(StatusValue.INACTIVE);
-      } else { // There are nameservers, so make sure INACTIVE isn't there.
-        removeStatusValue(StatusValue.INACTIVE);
-      }
-      // If there is no autorenew end time, set it to END_OF_TIME.
-      instance.autorenewEndTime = firstNonNull(getInstance().autorenewEndTime, END_OF_TIME);
-
-      checkArgumentNotNull(emptyToNull(instance.fullyQualifiedDomainName), "Missing domainName");
-      checkArgumentNotNull(instance.getRegistrant(), "Missing registrant");
-      instance.tld = getTldFromDomainName(instance.fullyQualifiedDomainName);
-
-      T newDomain = super.build();
-      // Hibernate throws exception if gracePeriods or dsData is null because we enabled all
-      // cascadable operations and orphan removal.
-      newDomain.gracePeriods =
-          newDomain.gracePeriods == null ? ImmutableSet.of() : newDomain.gracePeriods;
-      newDomain.dsData =
-          newDomain.dsData == null
-              ? ImmutableSet.of()
-              : newDomain.dsData.stream()
-                  .map(ds -> ds.cloneWithDomainRepoId(instance.getRepoId()))
-                  .collect(toImmutableSet());
-      return newDomain;
-    }
-
-    public B setDomainName(String domainName) {
-      checkArgument(
-          domainName.equals(canonicalizeHostname(domainName)),
-          "Domain name %s not in puny-coded, lower-case form",
-          domainName);
-      getInstance().fullyQualifiedDomainName = domainName;
-      return thisCastToDerived();
-    }
-
-    public B setDsData(ImmutableSet<DelegationSignerData> dsData) {
-      getInstance().dsData = dsData;
-      getInstance().resetUpdateTimestamp();
-      return thisCastToDerived();
-    }
-
-    public B setRegistrant(VKey<ContactResource> registrant) {
-      // Set the registrant field specifically.
-      getInstance().registrantContact = registrant;
-      return thisCastToDerived();
-    }
-
-    public B setAuthInfo(DomainAuthInfo authInfo) {
-      getInstance().authInfo = authInfo;
-      return thisCastToDerived();
-    }
-
-    public B setNameservers(VKey<HostResource> nameserver) {
-      getInstance().nsHosts = ImmutableSet.of(nameserver);
-      getInstance().resetUpdateTimestamp();
-      return thisCastToDerived();
-    }
-
-    public B setNameservers(ImmutableSet<VKey<HostResource>> nameservers) {
-      getInstance().nsHosts = forceEmptyToNull(nameservers);
-      getInstance().resetUpdateTimestamp();
-      return thisCastToDerived();
-    }
-
-    public B addNameserver(VKey<HostResource> nameserver) {
-      return addNameservers(ImmutableSet.of(nameserver));
-    }
-
-    public B addNameservers(ImmutableSet<VKey<HostResource>> nameservers) {
-      return setNameservers(
-          ImmutableSet.copyOf(Sets.union(getInstance().getNameservers(), nameservers)));
-    }
-
-    public B removeNameserver(VKey<HostResource> nameserver) {
-      return removeNameservers(ImmutableSet.of(nameserver));
-    }
-
-    public B removeNameservers(ImmutableSet<VKey<HostResource>> nameservers) {
-      return setNameservers(
-          ImmutableSet.copyOf(difference(getInstance().getNameservers(), nameservers)));
-    }
-
-    public B setContacts(DesignatedContact contact) {
-      return setContacts(ImmutableSet.of(contact));
-    }
-
-    public B setContacts(ImmutableSet<DesignatedContact> contacts) {
-      checkArgument(contacts.stream().noneMatch(IS_REGISTRANT), "Registrant cannot be a contact");
-
-      // Set the individual fields.
-      getInstance().setContactFields(contacts, false);
-      return thisCastToDerived();
-    }
-
-    public B addContacts(ImmutableSet<DesignatedContact> contacts) {
-      return setContacts(ImmutableSet.copyOf(Sets.union(getInstance().getContacts(), contacts)));
-    }
-
-    public B removeContacts(ImmutableSet<DesignatedContact> contacts) {
-      return setContacts(ImmutableSet.copyOf(difference(getInstance().getContacts(), contacts)));
-    }
-
-    public B setLaunchNotice(LaunchNotice launchNotice) {
-      getInstance().launchNotice = launchNotice;
-      return thisCastToDerived();
-    }
-
-    public B setIdnTableName(String idnTableName) {
-      getInstance().idnTableName = idnTableName;
-      return thisCastToDerived();
-    }
-
-    public B setSubordinateHosts(ImmutableSet<String> subordinateHosts) {
-      getInstance().subordinateHosts = subordinateHosts;
-      return thisCastToDerived();
-    }
-
-    public B addSubordinateHost(String hostToAdd) {
-      return setSubordinateHosts(
-          ImmutableSet.copyOf(union(getInstance().getSubordinateHosts(), hostToAdd)));
-    }
-
-    public B removeSubordinateHost(String hostToRemove) {
-      return setSubordinateHosts(
-          ImmutableSet.copyOf(
-              CollectionUtils.difference(getInstance().getSubordinateHosts(), hostToRemove)));
-    }
-
-    public B setRegistrationExpirationTime(DateTime registrationExpirationTime) {
-      getInstance().registrationExpirationTime = registrationExpirationTime;
-      return thisCastToDerived();
-    }
-
-    public B setDeletePollMessage(VKey<PollMessage.OneTime> deletePollMessage) {
-      getInstance().deletePollMessage = deletePollMessage;
-      return thisCastToDerived();
-    }
-
-    public B setAutorenewBillingEvent(VKey<BillingEvent.Recurring> autorenewBillingEvent) {
-      getInstance().autorenewBillingEvent = autorenewBillingEvent;
-      return thisCastToDerived();
-    }
-
-    public B setAutorenewPollMessage(
-        @Nullable VKey<PollMessage.Autorenew> autorenewPollMessage,
-        @Nullable Long autorenewPollMessageHistoryId) {
-      getInstance().autorenewPollMessage = autorenewPollMessage;
-      getInstance().autorenewPollMessageHistoryId = autorenewPollMessageHistoryId;
-      return thisCastToDerived();
-    }
-
-    public B setDnsRefreshRequestTime(Optional<DateTime> dnsRefreshRequestTime) {
-      getInstance().dnsRefreshRequestTime = dnsRefreshRequestTime.orElse(null);
-      return thisCastToDerived();
-    }
-
-    public B setSmdId(String smdId) {
-      getInstance().smdId = smdId;
-      return thisCastToDerived();
-    }
-
-    public B setGracePeriods(ImmutableSet<GracePeriod> gracePeriods) {
-      getInstance().gracePeriods = gracePeriods;
-      getInstance().resetUpdateTimestamp();
-      return thisCastToDerived();
-    }
-
-    public B addGracePeriod(GracePeriod gracePeriod) {
-      getInstance().gracePeriods = union(getInstance().getGracePeriods(), gracePeriod);
-      getInstance().resetUpdateTimestamp();
-      return thisCastToDerived();
-    }
-
-    public B removeGracePeriod(GracePeriod gracePeriod) {
-      getInstance().gracePeriods =
-          CollectionUtils.difference(getInstance().getGracePeriods(), gracePeriod);
-      getInstance().resetUpdateTimestamp();
-      return thisCastToDerived();
-    }
-
-    /**
-     * Sets the autorenew end time, or clears it if empty is passed.
-     *
-     * <p>Note that {@link DateTimeUtils#END_OF_TIME} is used as a sentinel value in the database
-     * representation to signify that autorenew doesn't end, and is mapped to empty here for the
-     * purposes of more legible business logic.
-     */
-    public B setAutorenewEndTime(Optional<DateTime> autorenewEndTime) {
-      getInstance().autorenewEndTime = autorenewEndTime.orElse(END_OF_TIME);
-      return thisCastToDerived();
-    }
-
-    @Override
-    public B setTransferData(DomainTransferData transferData) {
-      getInstance().transferData = transferData;
-      return thisCastToDerived();
-    }
-
-    @Override
-    public B setLastTransferTime(DateTime lastTransferTime) {
-      getInstance().lastTransferTime = lastTransferTime;
-      return thisCastToDerived();
-    }
-  }
-}

core/src/main/java/google/registry/model/domain/DomainHistory.java

@@ -59,8 +59,8 @@ import org.hibernate.Hibernate;
  * A persisted history entry representing an EPP modification to a domain.
  *
  * <p>In addition to the general history fields (e.g. action time, registrar ID) we also persist a
- * copy of the domain entity at this point in time. We persist a raw {@link DomainContent} so that
- * the foreign-keyed fields in that class can refer to this object.
+ * copy of the domain entity at this point in time. We persist a raw {@link DomainBase} so that the
+ * foreign-keyed fields in that class can refer to this object.
  *
  * <p>This class is only marked as a Datastore entity subclass and registered with Objectify so that
  * when building it its ID can be auto-populated by Objectify. It is converted to its superclass
@@ -80,9 +80,9 @@ import org.hibernate.Hibernate;
 @IdClass(DomainHistoryId.class)
 public class DomainHistory extends HistoryEntry {
 
-  // Store DomainContent instead of DomainBase so we don't pick up its @Id
+  // Store DomainBase instead of Domain so we don't pick up its @Id
   // Nullable for the sake of pre-Registry-3.0 history objects
-  @DoNotCompare @Nullable DomainContent domainContent;
+  @DoNotCompare @Nullable DomainBase domainBase;
 
   @Id
   @Access(AccessType.PROPERTY)
@@ -95,12 +95,12 @@ public class DomainHistory extends HistoryEntry {
   /** This method is private because it is only used by Hibernate. */
   @SuppressWarnings("unused")
   private void setDomainRepoId(String domainRepoId) {
-    parent = Key.create(DomainBase.class, domainRepoId);
+    parent = Key.create(Domain.class, domainRepoId);
   }
 
-  // We could have reused domainContent.nsHosts here, but Hibernate throws a weird exception after
+  // We could have reused domainBase.nsHosts here, but Hibernate throws a weird exception after
   // we change to use a composite primary key.
-  // TODO(b/166776754): Investigate if we can reuse domainContent.nsHosts for storing host keys.
+  // TODO(b/166776754): Investigate if we can reuse domainBase.nsHosts for storing host keys.
   @DoNotCompare
   @ElementCollection
   @JoinTable(
@@ -232,18 +232,18 @@ public class DomainHistory extends HistoryEntry {
   }
 
   /**
-   * The values of all the fields on the {@link DomainContent} object after the action represented
-   * by this history object was executed.
+   * The values of all the fields on the {@link DomainBase} object after the action represented by
+   * this history object was executed.
    *
    * <p>Will be absent for objects created prior to the Registry 3.0 SQL migration.
    */
-  public Optional<DomainContent> getDomainContent() {
-    return Optional.ofNullable(domainContent);
+  public Optional<DomainBase> getDomainBase() {
+    return Optional.ofNullable(domainBase);
   }
 
-  /** The key to the {@link DomainBase} this is based off of. */
-  public VKey<DomainBase> getParentVKey() {
-    return VKey.create(DomainBase.class, getDomainRepoId());
+  /** The key to the {@link Domain} this is based off of. */
+  public VKey<Domain> getParentVKey() {
+    return VKey.create(Domain.class, getDomainRepoId());
   }
 
   public Set<GracePeriodHistory> getGracePeriodHistories() {
@@ -259,8 +259,7 @@ public class DomainHistory extends HistoryEntry {
 
   @Override
   public Optional<? extends EppResource> getResourceAtPointInTime() {
-    return getDomainContent()
-        .map(domainContent -> new DomainBase.Builder().copyFrom(domainContent).build());
+    return getDomainBase().map(domainBase -> new Domain.Builder().copyFrom(domainBase).build());
   }
 
   @PostLoad
@@ -271,39 +270,39 @@ public class DomainHistory extends HistoryEntry {
     Hibernate.initialize(dsDataHistories);
     Hibernate.initialize(gracePeriodHistories);
 
-    if (domainContent != null) {
-      domainContent.nsHosts = nullToEmptyImmutableCopy(nsHosts);
-      domainContent.gracePeriods =
+    if (domainBase != null) {
+      domainBase.nsHosts = nullToEmptyImmutableCopy(nsHosts);
+      domainBase.gracePeriods =
           gracePeriodHistories.stream()
               .map(GracePeriod::createFromHistory)
               .collect(toImmutableSet());
-      domainContent.dsData =
+      domainBase.dsData =
           dsDataHistories.stream().map(DelegationSignerData::create).collect(toImmutableSet());
       // Normally Hibernate would see that the domain fields are all null and would fill
-      // domainContent with a null object. Unfortunately, the updateTimestamp is never null in SQL.
-      if (domainContent.getDomainName() == null) {
-        domainContent = null;
+      // domainBase with a null object. Unfortunately, the updateTimestamp is never null in SQL.
+      if (domainBase.getDomainName() == null) {
+        domainBase = null;
       } else {
-        if (domainContent.getRepoId() == null) {
-          // domainContent still hasn't been fully constructed yet, so it's ok to go in and mutate
+        if (domainBase.getRepoId() == null) {
+          // domainBase still hasn't been fully constructed yet, so it's ok to go in and mutate
           // it.  In fact, we have to because going through the builder causes the hash codes of
           // contained objects to be calculated prematurely.
-          domainContent.setRepoId(parent.getName());
+          domainBase.setRepoId(parent.getName());
         }
       }
     }
   }
 
   private static void fillAuxiliaryFieldsFromDomain(DomainHistory domainHistory) {
-    if (domainHistory.domainContent != null) {
-      domainHistory.nsHosts = nullToEmptyImmutableCopy(domainHistory.domainContent.nsHosts);
+    if (domainHistory.domainBase != null) {
+      domainHistory.nsHosts = nullToEmptyImmutableCopy(domainHistory.domainBase.nsHosts);
       domainHistory.dsDataHistories =
-          nullToEmptyImmutableCopy(domainHistory.domainContent.getDsData()).stream()
+          nullToEmptyImmutableCopy(domainHistory.domainBase.getDsData()).stream()
               .filter(dsData -> dsData.getDigest() != null && dsData.getDigest().length > 0)
               .map(dsData -> DomainDsDataHistory.createFrom(domainHistory.id, dsData))
               .collect(toImmutableSet());
       domainHistory.gracePeriodHistories =
-          nullToEmptyImmutableCopy(domainHistory.domainContent.getGracePeriods()).stream()
+          nullToEmptyImmutableCopy(domainHistory.domainBase.getGracePeriods()).stream()
               .map(gracePeriod -> GracePeriodHistory.createFrom(domainHistory.id, gracePeriod))
               .collect(toImmutableSet());
     } else {
@@ -372,35 +371,35 @@ public class DomainHistory extends HistoryEntry {
       super(instance);
     }
 
-    public Builder setDomain(@Nullable DomainContent domainContent) {
+    public Builder setDomain(@Nullable DomainBase domainBase) {
       // Nullable for the sake of pre-Registry-3.0 history objects
-      if (domainContent == null) {
+      if (domainBase == null) {
         return this;
       }
-      // TODO(b/203609982): if actual type of domainContent is DomainBase, convert to DomainContent
-      // Note: a DomainHistory fetched by JPA has DomainContent in this field. Allowing DomainBase
+      // TODO(b/203609982): if actual type of domainBase is Domain, convert to DomainBase
+      // Note: a DomainHistory fetched by JPA has DomainBase in this field. Allowing Domain
       // in the setter makes equality checks messy.
-      getInstance().domainContent = domainContent;
-      if (domainContent instanceof DomainBase) {
-        super.setParent(domainContent);
+      getInstance().domainBase = domainBase;
+      if (domainBase instanceof Domain) {
+        super.setParent(domainBase);
       } else {
-        super.setParent(Key.create(DomainBase.class, domainContent.getRepoId()));
+        super.setParent(Key.create(Domain.class, domainBase.getRepoId()));
       }
       return this;
     }
 
     public Builder setDomainRepoId(String domainRepoId) {
-      getInstance().parent = Key.create(DomainBase.class, domainRepoId);
+      getInstance().parent = Key.create(Domain.class, domainRepoId);
       return this;
     }
 
     @Override
     public DomainHistory build() {
       DomainHistory instance = super.build();
-      // TODO(b/171990736): Assert instance.domainContent is not null after database migration.
-      // Note that we cannot assert that instance.domainContent is not null here because this
+      // TODO(b/171990736): Assert instance.domainBase is not null after database migration.
+      // Note that we cannot assert that instance.domainBase is not null here because this
       // builder is also used to convert legacy HistoryEntry objects to DomainHistory, when
-      // domainContent is not available.
+      // domainBase is not available.
       fillAuxiliaryFieldsFromDomain(instance);
       return instance;
     }

core/src/main/java/google/registry/model/domain/GracePeriod.java

@@ -37,8 +37,8 @@ import org.joda.time.DateTime;
 /**
  * A domain grace period with an expiration time.
  *
- * <p>When a grace period expires, it is lazily removed from the {@link DomainBase} the next time
- * the resource is loaded from Datastore.
+ * <p>When a grace period expires, it is lazily removed from the {@link Domain} the next time the
+ * resource is loaded from Datastore.
  */
 @Embed
 @Entity

core/src/main/java/google/registry/model/domain/GracePeriodBase.java

@@ -65,6 +65,7 @@ public class GracePeriodBase extends ImmutableObject implements UnsafeSerializab
   // NB: Would @IgnoreSave(IfNull.class), but not allowed for @Embed collections.
   @Access(AccessType.FIELD)
   @Column(name = "billing_event_id")
+  @Ignore
   VKey<BillingEvent.OneTime> billingEventOneTime = null;
 
   /**
@@ -74,6 +75,7 @@ public class GracePeriodBase extends ImmutableObject implements UnsafeSerializab
   // NB: Would @IgnoreSave(IfNull.class), but not allowed for @Embed collections.
   @Access(AccessType.FIELD)
   @Column(name = "billing_recurrence_id")
+  @Ignore
   VKey<BillingEvent.Recurring> billingEventRecurring = null;
 
   public long getGracePeriodId() {

core/src/main/java/google/registry/model/domain/token/AllocationToken.java

@@ -168,6 +168,7 @@ public class AllocationToken extends BackupGroupRoot implements Buildable {
 
   @Enumerated(EnumType.STRING)
   @Column(name = "renewalPriceBehavior", nullable = false)
+  @Ignore
   RenewalPriceBehavior renewalPriceBehavior = RenewalPriceBehavior.DEFAULT;
 
   @Enumerated(EnumType.STRING)

core/src/main/java/google/registry/model/eppcommon/StatusValue.java

@@ -22,8 +22,8 @@ import com.google.common.collect.ImmutableSet;
 import google.registry.model.EppResource;
 import google.registry.model.contact.ContactBase;
 import google.registry.model.contact.ContactResource;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainBase;
-import google.registry.model.domain.DomainContent;
 import google.registry.model.host.HostBase;
 import google.registry.model.host.HostResource;
 import google.registry.model.translators.EnumToAttributeAdapter.EppEnum;
@@ -132,12 +132,12 @@ public enum StatusValue implements EppEnum {
     ALL(
         ContactBase.class,
         ContactResource.class,
-        DomainContent.class,
         DomainBase.class,
+        Domain.class,
         HostBase.class,
         HostResource.class),
     NONE,
-    DOMAINS(DomainContent.class, DomainBase.class);
+    DOMAINS(DomainBase.class, Domain.class);
 
     private final ImmutableSet<Class<? extends EppResource>> classes;
 

core/src/main/java/google/registry/model/host/HostBase.java

@@ -26,7 +26,7 @@ import com.googlecode.objectify.annotation.IgnoreSave;
 import com.googlecode.objectify.annotation.Index;
 import com.googlecode.objectify.condition.IfNull;
 import google.registry.model.EppResource;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.transfer.TransferData;
 import google.registry.persistence.VKey;
 import java.net.InetAddress;
@@ -76,7 +76,7 @@ public class HostBase extends EppResource {
   @Index
   @IgnoreSave(IfNull.class)
   @DoNotHydrate
-  VKey<DomainBase> superordinateDomain;
+  VKey<Domain> superordinateDomain;
 
   /**
    * The time that this resource was last transferred.
@@ -98,7 +98,7 @@ public class HostBase extends EppResource {
     return fullyQualifiedHostName;
   }
 
-  public VKey<DomainBase> getSuperordinateDomain() {
+  public VKey<Domain> getSuperordinateDomain() {
     return superordinateDomain;
   }
 
@@ -155,7 +155,7 @@ public class HostBase extends EppResource {
    *     {@link #superordinateDomain} field. Passing it as a parameter allows the caller to control
    *     the degree of consistency used to load it.
    */
-  public DateTime computeLastTransferTime(@Nullable DomainBase superordinateDomain) {
+  public DateTime computeLastTransferTime(@Nullable Domain superordinateDomain) {
     if (!isSubordinate()) {
       checkArgument(superordinateDomain == null);
       return getLastTransferTime();
@@ -222,7 +222,7 @@ public class HostBase extends EppResource {
           ImmutableSet.copyOf(difference(getInstance().getInetAddresses(), inetAddresses)));
     }
 
-    public B setSuperordinateDomain(VKey<DomainBase> superordinateDomain) {
+    public B setSuperordinateDomain(VKey<Domain> superordinateDomain) {
       getInstance().superordinateDomain = superordinateDomain;
       return thisCastToDerived();
     }

core/src/main/java/google/registry/model/index/ForeignKeyIndex.java

@@ -48,7 +48,7 @@ import google.registry.model.EppResource;
 import google.registry.model.annotations.DeleteAfterMigration;
 import google.registry.model.annotations.ReportedOn;
 import google.registry.model.contact.ContactResource;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.host.HostResource;
 import google.registry.persistence.VKey;
 import google.registry.persistence.transaction.CriteriaQueryBuilder;
@@ -75,10 +75,10 @@ public abstract class ForeignKeyIndex<E extends EppResource> extends BackupGroup
   @Entity
   public static class ForeignKeyContactIndex extends ForeignKeyIndex<ContactResource> {}
 
-  /** The {@link ForeignKeyIndex} type for {@link DomainBase} entities. */
+  /** The {@link ForeignKeyIndex} type for {@link Domain} entities. */
   @ReportedOn
   @Entity
-  public static class ForeignKeyDomainIndex extends ForeignKeyIndex<DomainBase> {}
+  public static class ForeignKeyDomainIndex extends ForeignKeyIndex<Domain> {}
 
   /** The {@link ForeignKeyIndex} type for {@link HostResource} entities. */
   @ReportedOn
@@ -90,14 +90,14 @@ public abstract class ForeignKeyIndex<E extends EppResource> extends BackupGroup
       RESOURCE_CLASS_TO_FKI_CLASS =
           ImmutableBiMap.of(
               ContactResource.class, ForeignKeyContactIndex.class,
-              DomainBase.class, ForeignKeyDomainIndex.class,
+              Domain.class, ForeignKeyDomainIndex.class,
               HostResource.class, ForeignKeyHostIndex.class);
 
   private static final ImmutableMap<Class<? extends EppResource>, String>
       RESOURCE_CLASS_TO_FKI_PROPERTY =
           ImmutableMap.of(
               ContactResource.class, "contactId",
-              DomainBase.class, "fullyQualifiedDomainName",
+              Domain.class, "fullyQualifiedDomainName",
               HostResource.class, "fullyQualifiedHostName");
 
   @Id String foreignKey;

core/src/main/java/google/registry/model/package-info.java

@@ -33,7 +33,7 @@ import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
  * via Objectify.
  *
  * <p>All first class entities are represented as a resource class - {@link
- * google.registry.model.domain.DomainBase}, {@link google.registry.model.host.HostResource}, {@link
+ * google.registry.model.domain.Domain}, {@link google.registry.model.host.HostResource}, {@link
  * google.registry.model.contact.ContactResource}, and {@link
  * google.registry.model.registrar.Registrar}. Resource objects are written in a single shared
  * entity group per TLD. All commands that operate on those entities are grouped in a "Command"

core/src/main/java/google/registry/model/poll/PollMessage.java

@@ -35,7 +35,7 @@ import google.registry.model.annotations.ReportedOn;
 import google.registry.model.contact.ContactHistory;
 import google.registry.model.contact.ContactHistory.ContactHistoryId;
 import google.registry.model.contact.ContactResource;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainHistory;
 import google.registry.model.domain.DomainHistory.DomainHistoryId;
 import google.registry.model.domain.DomainRenewData;
@@ -103,7 +103,7 @@ public abstract class PollMessage extends ImmutableObject
 
   /** Indicates the type of entity the poll message is for. */
   public enum Type {
-    DOMAIN(1L, DomainBase.class),
+    DOMAIN(1L, Domain.class),
     CONTACT(2L, ContactResource.class),
     HOST(3L, HostResource.class);
 

core/src/main/java/google/registry/model/reporting/HistoryEntry.java

@@ -38,8 +38,8 @@ import google.registry.model.contact.ContactBase;
 import google.registry.model.contact.ContactHistory;
 import google.registry.model.contact.ContactHistory.ContactHistoryId;
 import google.registry.model.contact.ContactResource;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainBase;
-import google.registry.model.domain.DomainContent;
 import google.registry.model.domain.DomainHistory;
 import google.registry.model.domain.DomainHistory.DomainHistoryId;
 import google.registry.model.domain.Period;
@@ -386,7 +386,7 @@ public class HistoryEntry extends ImmutableObject implements Buildable, UnsafeSe
     String parentKind = getParent().getKind();
     final HistoryEntry resultEntity;
     // can't use a switch statement since we're calling getKind()
-    if (parentKind.equals(getKind(DomainBase.class))) {
+    if (parentKind.equals(getKind(Domain.class))) {
       resultEntity =
           new DomainHistory.Builder().copyFrom(this).setDomainRepoId(parent.getName()).build();
     } else if (parentKind.equals(getKind(HostResource.class))) {
@@ -408,7 +408,7 @@ public class HistoryEntry extends ImmutableObject implements Buildable, UnsafeSe
     long id = key.getId();
     Key<EppResource> parent = key.getParent();
     String parentKind = parent.getKind();
-    if (parentKind.equals(getKind(DomainBase.class))) {
+    if (parentKind.equals(getKind(Domain.class))) {
       return VKey.create(
           DomainHistory.class,
           new DomainHistoryId(repoId, id),
@@ -537,8 +537,8 @@ public class HistoryEntry extends ImmutableObject implements Buildable, UnsafeSe
 
   public static <E extends EppResource>
       HistoryEntry.Builder<? extends HistoryEntry, ?> createBuilderForResource(E parent) {
-    if (parent instanceof DomainContent) {
-      return new DomainHistory.Builder().setDomain((DomainContent) parent);
+    if (parent instanceof DomainBase) {
+      return new DomainHistory.Builder().setDomain((DomainBase) parent);
     } else if (parent instanceof ContactBase) {
       return new ContactHistory.Builder().setContact((ContactBase) parent);
     } else if (parent instanceof HostBase) {

core/src/main/java/google/registry/model/reporting/HistoryEntryDao.java

@@ -27,7 +27,7 @@ import com.google.common.collect.Streams;
 import google.registry.model.EppResource;
 import google.registry.model.contact.ContactHistory;
 import google.registry.model.contact.ContactResource;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainHistory;
 import google.registry.model.host.HostHistory;
 import google.registry.model.host.HostResource;
@@ -53,7 +53,7 @@ public class HistoryEntryDao {
           ImmutableMap.of(
               ContactResource.class,
               ContactHistory.class,
-              DomainBase.class,
+              Domain.class,
               DomainHistory.class,
               HostResource.class,
               HostHistory.class);

core/src/main/java/google/registry/model/server/ServerSecret.java

@@ -66,7 +66,7 @@ public class ServerSecret extends CrossTldSingleton {
               Optional<ServerSecret> secret = tm().loadSingleton(ServerSecret.class);
               if (!secret.isPresent()) {
                 secret = Optional.of(create(UUID.randomUUID()));
-                tm().insertWithoutBackup(secret.get());
+                tm().insert(secret.get());
               }
               return secret.get();
             });

core/src/main/java/google/registry/model/tmch/TmchCrl.java

@@ -56,7 +56,7 @@ public final class TmchCrl extends CrossTldSingleton {
               tmchCrl.updated = jpaTm().getTransactionTime();
               tmchCrl.crl = checkNotNull(crl, "crl");
               tmchCrl.url = checkNotNull(url, "url");
-              jpaTm().transactNew(() -> jpaTm().putWithoutBackup(tmchCrl));
+              jpaTm().put(tmchCrl);
             });
   }
 

core/src/main/java/google/registry/model/transfer/DomainTransferData.java

@@ -85,8 +85,8 @@ public class DomainTransferData extends TransferData<DomainTransferData.Builder>
    * <p>This field should be null if there is not currently a pending transfer or if the object
    * being transferred is not a domain.
    */
-  @IgnoreSave(IfNull.class)
   @Column(name = "transfer_billing_event_id")
+  @Ignore
   VKey<BillingEvent.OneTime> serverApproveBillingEvent;
 
   /**
@@ -95,8 +95,8 @@ public class DomainTransferData extends TransferData<DomainTransferData.Builder>
    * <p>This field should be null if there is not currently a pending transfer or if the object
    * being transferred is not a domain.
    */
-  @IgnoreSave(IfNull.class)
   @Column(name = "transfer_billing_recurrence_id")
+  @Ignore
   VKey<BillingEvent.Recurring> serverApproveAutorenewEvent;
 
   /**

core/src/main/java/google/registry/model/translators/EppHistoryVKeyTranslatorFactory.java

@@ -21,8 +21,6 @@ import com.google.appengine.api.datastore.Key;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
-import google.registry.persistence.BillingVKey.BillingEventVKey;
-import google.registry.persistence.BillingVKey.BillingRecurrenceVKey;
 import google.registry.persistence.DomainHistoryVKey;
 import google.registry.persistence.EppHistoryVKey;
 import java.lang.reflect.Constructor;
@@ -45,8 +43,7 @@ public class EppHistoryVKeyTranslatorFactory
   // key, e.g. the map key for ContactPollMessageVKey is "ContactResource/HistoryEntry/PollMessage".
   @VisibleForTesting
   static final ImmutableMap<String, Class<? extends EppHistoryVKey>> kindPathToVKeyClass =
-      ImmutableSet.of(DomainHistoryVKey.class, BillingEventVKey.class, BillingRecurrenceVKey.class)
-          .stream()
+      ImmutableSet.of(DomainHistoryVKey.class).stream()
           .collect(toImmutableMap(EppHistoryVKeyTranslatorFactory::getKindPath, identity()));
 
   /**

core/src/main/java/google/registry/persistence/BillingVKey.java

@@ -1,125 +0,0 @@
-// Copyright 2020 The Nomulus Authors. All Rights Reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package google.registry.persistence;
-
-
-import com.googlecode.objectify.Key;
-import google.registry.model.billing.BillingEvent;
-import google.registry.model.billing.BillingEvent.OneTime;
-import google.registry.model.billing.BillingEvent.Recurring;
-import google.registry.model.domain.DomainBase;
-import google.registry.model.reporting.HistoryEntry;
-import java.io.Serializable;
-import javax.annotation.Nullable;
-import javax.persistence.AttributeOverride;
-import javax.persistence.AttributeOverrides;
-import javax.persistence.Column;
-import javax.persistence.Embeddable;
-import javax.persistence.MappedSuperclass;
-
-/** Base class for {@link BillingEvent}'s {@link VKey}. */
-@MappedSuperclass
-public abstract class BillingVKey<K> extends EppHistoryVKey<K, DomainBase> {
-  Long billingId;
-
-  // Hibernate requires a default constructor.
-  BillingVKey() {}
-
-  BillingVKey(String repoId, long historyRevisionId, long billingId) {
-    super(repoId, historyRevisionId);
-    this.billingId = billingId;
-  }
-
-  Key<HistoryEntry> createHistoryEntryKey() {
-    return Key.create(Key.create(DomainBase.class, repoId), HistoryEntry.class, historyRevisionId);
-  }
-
-  @Override
-  public Serializable createSqlKey() {
-    return billingId;
-  }
-
-  /** VKey class for {@link BillingEvent.OneTime} that belongs to a {@link DomainBase} entity. */
-  @Embeddable
-  @AttributeOverrides({
-    @AttributeOverride(name = "repoId", column = @Column(name = "billing_event_domain_repo_id")),
-    @AttributeOverride(
-        name = "historyRevisionId",
-        column = @Column(name = "billing_event_history_id")),
-    @AttributeOverride(name = "billingId", column = @Column(name = "billing_event_id"))
-  })
-  public static class BillingEventVKey extends BillingVKey<OneTime> {
-
-    // Hibernate requires this default constructor
-    private BillingEventVKey() {}
-
-    private BillingEventVKey(String repoId, long historyRevisionId, long billingEventId) {
-      super(repoId, historyRevisionId, billingEventId);
-    }
-
-    /** Creates a {@link BillingEventVKey} instance from the given {@link Key} instance. */
-    public static BillingEventVKey create(@Nullable Key<BillingEvent.OneTime> ofyKey) {
-      if (ofyKey == null) {
-        return null;
-      }
-      long billingEventId = ofyKey.getId();
-      long historyRevisionId = ofyKey.getParent().getId();
-      String repoId = ofyKey.getParent().getParent().getName();
-      return new BillingEventVKey(repoId, historyRevisionId, billingEventId);
-    }
-
-    /** Creates a {@link BillingEventVKey} instance from the given {@link VKey} instance. */
-    public static BillingEventVKey create(@Nullable VKey<BillingEvent.OneTime> vKey) {
-      return vKey == null ? null : new BillingEventVKey(null, 0, (Long) vKey.getSqlKey());
-    }
-  }
-
-  /** VKey class for {@link BillingEvent.Recurring} that belongs to a {@link DomainBase} entity. */
-  @Embeddable
-  @AttributeOverrides({
-    @AttributeOverride(
-        name = "repoId",
-        column = @Column(name = "billing_recurrence_domain_repo_id")),
-    @AttributeOverride(
-        name = "historyRevisionId",
-        column = @Column(name = "billing_recurrence_history_id")),
-    @AttributeOverride(name = "billingId", column = @Column(name = "billing_recurrence_id"))
-  })
-  public static class BillingRecurrenceVKey extends BillingVKey<Recurring> {
-
-    // Hibernate requires this default constructor
-    private BillingRecurrenceVKey() {}
-
-    private BillingRecurrenceVKey(String repoId, long historyRevisionId, long billingEventId) {
-      super(repoId, historyRevisionId, billingEventId);
-    }
-
-    /** Creates a {@link BillingRecurrenceVKey} instance from the given {@link Key} instance. */
-    public static BillingRecurrenceVKey create(@Nullable Key<BillingEvent.Recurring> ofyKey) {
-      if (ofyKey == null) {
-        return null;
-      }
-      long billingEventId = ofyKey.getId();
-      long historyRevisionId = ofyKey.getParent().getId();
-      String repoId = ofyKey.getParent().getParent().getName();
-      return new BillingRecurrenceVKey(repoId, historyRevisionId, billingEventId);
-    }
-
-    /** Creates a {@link BillingRecurrenceVKey} instance from the given {@link VKey} instance. */
-    public static BillingRecurrenceVKey create(@Nullable VKey<BillingEvent.Recurring> vKey) {
-      return vKey == null ? null : new BillingRecurrenceVKey(null, 0, (Long) vKey.getSqlKey());
-    }
-  }
-}

core/src/main/java/google/registry/persistence/DomainHistoryVKey.java

@@ -17,16 +17,16 @@ package google.registry.persistence;
 import static google.registry.util.PreconditionsUtils.checkArgumentNotNull;
 
 import com.googlecode.objectify.Key;
-import google.registry.model.domain.DomainBase;
+import google.registry.model.domain.Domain;
 import google.registry.model.domain.DomainHistory;
 import google.registry.model.domain.DomainHistory.DomainHistoryId;
 import google.registry.model.reporting.HistoryEntry;
 import java.io.Serializable;
 import javax.persistence.Embeddable;
 
-/** {@link VKey} for {@link HistoryEntry} which parent is {@link DomainBase}. */
+/** {@link VKey} for {@link HistoryEntry} which parent is {@link Domain}. */
 @Embeddable
-public class DomainHistoryVKey extends EppHistoryVKey<HistoryEntry, DomainBase> {
+public class DomainHistoryVKey extends EppHistoryVKey<HistoryEntry, Domain> {
 
   // Hibernate requires a default constructor
   private DomainHistoryVKey() {}
@@ -52,6 +52,6 @@ public class DomainHistoryVKey extends EppHistoryVKey<HistoryEntry, DomainBase>
     return VKey.create(
         DomainHistory.class,
         createSqlKey(),
-        Key.create(Key.create(DomainBase.class, repoId), DomainHistory.class, historyRevisionId));
+        Key.create(Key.create(Domain.class, repoId), DomainHistory.class, historyRevisionId));
   }
 }