Refactor TransferData to remove unused fields in Contact table (#623)

* Add DomainTransferData and ContactTransferData

* Refactor TransferData to remove unused fields in Contact table

* Add scope for TransferData's type parameter

core/src/main/java/google/registry/flows/contact/ContactTransferRequestFlow.java

@@ -46,7 +46,7 @@ import google.registry.model.eppoutput.EppResponse;
 import google.registry.model.poll.PollMessage;
 import google.registry.model.reporting.HistoryEntry;
 import google.registry.model.reporting.IcannReportingTypes.ActivityReportField;
-import google.registry.model.transfer.TransferData;
+import google.registry.model.transfer.ContactTransferData;
 import google.registry.model.transfer.TransferStatus;
 import java.util.Optional;
 import javax.inject.Inject;
@@ -112,21 +112,22 @@ public final class ContactTransferRequestFlow implements TransactionalFlow {
         .setParent(Key.create(existingContact))
         .build();
     DateTime transferExpirationTime = now.plus(automaticTransferLength);
-    TransferData serverApproveTransferData = new TransferData.Builder()
-        .setTransferRequestTime(now)
-        .setTransferRequestTrid(trid)
-        .setGainingClientId(gainingClientId)
-        .setLosingClientId(losingClientId)
-        .setPendingTransferExpirationTime(transferExpirationTime)
-        .setTransferStatus(TransferStatus.SERVER_APPROVED)
-        .build();
+    ContactTransferData serverApproveTransferData =
+        new ContactTransferData.Builder()
+            .setTransferRequestTime(now)
+            .setTransferRequestTrid(trid)
+            .setGainingClientId(gainingClientId)
+            .setLosingClientId(losingClientId)
+            .setPendingTransferExpirationTime(transferExpirationTime)
+            .setTransferStatus(TransferStatus.SERVER_APPROVED)
+            .build();
     // If the transfer is server approved, this message will be sent to the losing registrar. */
     PollMessage serverApproveLosingPollMessage =
         createLosingTransferPollMessage(targetId, serverApproveTransferData, historyEntry);
     // If the transfer is server approved, this message will be sent to the gaining registrar. */
     PollMessage serverApproveGainingPollMessage =
         createGainingTransferPollMessage(targetId, serverApproveTransferData, historyEntry);
-    TransferData pendingTransferData =
+    ContactTransferData pendingTransferData =
         serverApproveTransferData
             .asBuilder()
             .setTransferStatus(TransferStatus.PENDING)

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

@@ -58,7 +58,7 @@ import google.registry.model.registry.Registry;
 import google.registry.model.reporting.DomainTransactionRecord;
 import google.registry.model.reporting.HistoryEntry;
 import google.registry.model.reporting.IcannReportingTypes.ActivityReportField;
-import google.registry.model.transfer.TransferData;
+import google.registry.model.transfer.DomainTransferData;
 import google.registry.model.transfer.TransferStatus;
 import java.util.Optional;
 import javax.inject.Inject;
@@ -112,7 +112,7 @@ public final class DomainTransferApproveFlow implements TransactionalFlow {
     if (!isSuperuser) {
       checkAllowedAccessToTld(clientId, tld);
     }
-    TransferData transferData = existingDomain.getTransferData();
+    DomainTransferData transferData = existingDomain.getTransferData();
     String gainingClientId = transferData.getGainingClientId();
     Registry registry = Registry.get(existingDomain.getTld());
     HistoryEntry historyEntry = buildHistoryEntry(existingDomain, registry, now, gainingClientId);

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

@@ -32,7 +32,7 @@ import google.registry.model.domain.DomainBase;
 import google.registry.model.eppcommon.AuthInfo;
 import google.registry.model.eppoutput.EppResponse;
 import google.registry.model.reporting.IcannReportingTypes.ActivityReportField;
-import google.registry.model.transfer.TransferData;
+import google.registry.model.transfer.DomainTransferData;
 import google.registry.model.transfer.TransferStatus;
 import google.registry.util.Clock;
 import java.util.Optional;
@@ -74,7 +74,7 @@ public final class DomainTransferQueryFlow implements Flow {
     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).
-    TransferData transferData = domain.getTransferData();
+    DomainTransferData transferData = domain.getTransferData();
     if (transferData.getTransferStatus() == null) {
       throw new NoTransferHistoryToQueryException();
     }

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

@@ -69,7 +69,7 @@ import google.registry.model.reporting.DomainTransactionRecord;
 import google.registry.model.reporting.DomainTransactionRecord.TransactionReportField;
 import google.registry.model.reporting.HistoryEntry;
 import google.registry.model.reporting.IcannReportingTypes.ActivityReportField;
-import google.registry.model.transfer.TransferData;
+import google.registry.model.transfer.DomainTransferData;
 import google.registry.model.transfer.TransferData.TransferServerApproveEntity;
 import google.registry.model.transfer.TransferResponse.DomainTransferResponse;
 import google.registry.model.transfer.TransferStatus;
@@ -198,9 +198,9 @@ public final class DomainTransferRequestFlow implements TransactionalFlow {
             feesAndCredits.map(FeesAndCredits::getTotalCost),
             now);
     // Create the transfer data that represents the pending transfer.
-    TransferData pendingTransferData =
+    DomainTransferData pendingTransferData =
         createPendingTransferData(
-            new TransferData.Builder()
+            new DomainTransferData.Builder()
                 .setTransferRequestTrid(trid)
                 .setTransferRequestTime(now)
                 .setGainingClientId(gainingClientId)

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

@@ -32,6 +32,7 @@ import google.registry.model.poll.PendingActionNotificationResponse.DomainPendin
 import google.registry.model.poll.PollMessage;
 import google.registry.model.registry.Registry;
 import google.registry.model.reporting.HistoryEntry;
+import google.registry.model.transfer.DomainTransferData;
 import google.registry.model.transfer.TransferData;
 import google.registry.model.transfer.TransferData.TransferServerApproveEntity;
 import google.registry.model.transfer.TransferResponse.DomainTransferResponse;
@@ -48,8 +49,8 @@ import org.joda.time.DateTime;
 public final class DomainTransferUtils {
 
   /** Sets up {@link TransferData} for a domain with links to entities for server approval. */
-  public static TransferData createPendingTransferData(
-      TransferData.Builder transferDataBuilder,
+  public static DomainTransferData createPendingTransferData(
+      DomainTransferData.Builder transferDataBuilder,
       ImmutableSet<TransferServerApproveEntity> serverApproveEntities,
       Period transferPeriod) {
     ImmutableSet.Builder<VKey<? extends TransferServerApproveEntity>> serverApproveEntityKeys =
@@ -110,8 +111,8 @@ public final class DomainTransferUtils {
       DateTime now) {
     String targetId = existingDomain.getFullyQualifiedDomainName();
     // Create a TransferData for the server-approve case to use for the speculative poll messages.
-    TransferData serverApproveTransferData =
-        new TransferData.Builder()
+    DomainTransferData serverApproveTransferData =
+        new DomainTransferData.Builder()
             .setTransferRequestTrid(trid)
             .setTransferRequestTime(now)
             .setGainingClientId(gainingClientId)

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

@@ -193,8 +193,8 @@ public abstract class EppResource extends BackupGroupRoot implements Buildable {
   public interface ForeignKeyedEppResource {}
 
   /** An interface for resources that have transfer data. */
-  public interface ResourceWithTransferData {
-    TransferData getTransferData();
+  public interface ResourceWithTransferData<T extends TransferData> {
+    T getTransferData();
 
     /**
      * The time that this resource was last transferred.
@@ -205,8 +205,9 @@ public abstract class EppResource extends BackupGroupRoot implements Buildable {
   }
 
   /** An interface for builders of resources that have transfer data. */
-  public interface BuilderWithTransferData<B extends BuilderWithTransferData<B>> {
-    B setTransferData(TransferData transferData);
+  public interface BuilderWithTransferData<
+      T extends TransferData, B extends BuilderWithTransferData<T, B>> {
+    B setTransferData(T transferData);
 
     /** Set the time when this resource was transferred. */
     B setLastTransferTime(DateTime lastTransferTime);

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

@@ -39,6 +39,7 @@ import google.registry.model.index.ForeignKeyIndex;
 import google.registry.model.ofy.CommitLogManifest;
 import google.registry.model.ofy.CommitLogMutation;
 import google.registry.model.registry.Registry;
+import google.registry.model.transfer.DomainTransferData;
 import google.registry.model.transfer.TransferData;
 import google.registry.model.transfer.TransferStatus;
 import java.util.List;
@@ -222,17 +223,23 @@ public final class EppResourceUtils {
   }
 
   /** Process an automatic transfer on a resource. */
-  public static <B extends EppResource.Builder<?, B> & BuilderWithTransferData<B>>
+  public static <
+          T extends TransferData,
+          B extends EppResource.Builder<?, B> & BuilderWithTransferData<T, B>>
       void setAutomaticTransferSuccessProperties(B builder, TransferData transferData) {
     checkArgument(TransferStatus.PENDING.equals(transferData.getTransferStatus()));
-    builder.removeStatusValue(StatusValue.PENDING_TRANSFER)
-        .setTransferData(transferData.asBuilder()
-            .setTransferStatus(TransferStatus.SERVER_APPROVED)
-            .setServerApproveEntities(null)
-            .setServerApproveBillingEvent(null)
-            .setServerApproveAutorenewEvent(null)
-            .setServerApproveAutorenewPollMessage(null)
-            .build())
+    TransferData.Builder transferDataBuilder = transferData.asBuilder();
+    transferDataBuilder.setTransferStatus(TransferStatus.SERVER_APPROVED);
+    transferDataBuilder.setServerApproveEntities(null);
+    if (transferData instanceof DomainTransferData) {
+      ((DomainTransferData.Builder) transferDataBuilder)
+          .setServerApproveBillingEvent(null)
+          .setServerApproveAutorenewEvent(null)
+          .setServerApproveAutorenewPollMessage(null);
+    }
+    builder
+        .removeStatusValue(StatusValue.PENDING_TRANSFER)
+        .setTransferData((T) transferDataBuilder.build())
         .setLastTransferTime(transferData.getPendingTransferExpirationTime())
         .setPersistedCurrentSponsorClientId(transferData.getGainingClientId());
   }
@@ -245,10 +252,11 @@ public final class EppResourceUtils {
    * </ul>
    */
   public static <
-          T extends EppResource & ResourceWithTransferData,
-          B extends EppResource.Builder<?, B> & BuilderWithTransferData<B>>
-      void projectResourceOntoBuilderAtTime(T resource, B builder, DateTime now) {
-    TransferData transferData = resource.getTransferData();
+          T extends TransferData,
+          E extends EppResource & ResourceWithTransferData<T>,
+          B extends EppResource.Builder<?, B> & BuilderWithTransferData<T, B>>
+      void projectResourceOntoBuilderAtTime(E resource, B builder, DateTime now) {
+    T transferData = resource.getTransferData();
     // If there's a pending transfer that has expired, process it.
     DateTime expirationTime = transferData.getPendingTransferExpirationTime();
     if (TransferStatus.PENDING.equals(transferData.getTransferStatus())

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

@@ -36,6 +36,7 @@ import google.registry.model.poll.PendingActionNotificationResponse.ContactPendi
 import google.registry.model.poll.PendingActionNotificationResponse.DomainPendingActionNotificationResponse;
 import google.registry.model.poll.PollMessage;
 import google.registry.model.reporting.HistoryEntry;
+import google.registry.model.transfer.DomainTransferData;
 import google.registry.model.transfer.TransferData;
 import google.registry.model.transfer.TransferResponse;
 import google.registry.model.transfer.TransferResponse.ContactTransferResponse;
@@ -63,12 +64,13 @@ public final class ResourceTransferUtils {
     if (eppResource instanceof ContactResource) {
       builder = new ContactTransferResponse.Builder().setContactId(eppResource.getForeignKey());
     } else {
+      DomainTransferData domainTransferData = (DomainTransferData) transferData;
       builder =
           new DomainTransferResponse.Builder()
               .setFullyQualifiedDomainName(eppResource.getForeignKey())
               .setExtendedRegistrationExpirationTime(
-                  ADD_EXDATE_STATUSES.contains(transferData.getTransferStatus())
-                      ? transferData.getTransferredRegistrationExpirationTime()
+                  ADD_EXDATE_STATUSES.contains(domainTransferData.getTransferStatus())
+                      ? domainTransferData.getTransferredRegistrationExpirationTime()
                       : null);
     }
     builder.setGainingClientId(transferData.getGainingClientId())
@@ -142,23 +144,25 @@ public final class ResourceTransferUtils {
    */
   private static <
           R extends EppResource & ResourceWithTransferData,
-          B extends EppResource.Builder<R, B> & BuilderWithTransferData<B>>
+          B extends EppResource.Builder<R, B> & BuilderWithTransferData<TransferData, B>>
       B resolvePendingTransfer(R resource, TransferStatus transferStatus, DateTime now) {
     checkArgument(
         resource.getStatusValues().contains(StatusValue.PENDING_TRANSFER),
         "Resource is not in pending transfer status.");
-    checkArgument(
-        !TransferData.EMPTY.equals(resource.getTransferData()),
-        "No old transfer data to resolve.");
+    checkArgument(!resource.getTransferData().isEmpty(), "No old transfer data to resolve.");
     @SuppressWarnings("unchecked")
     B builder = (B) resource.asBuilder();
+
     return builder
         .removeStatusValue(StatusValue.PENDING_TRANSFER)
         .setTransferData(
-            resource.getTransferData().copyConstantFieldsToBuilder()
-                .setTransferStatus(transferStatus)
-                .setPendingTransferExpirationTime(checkNotNull(now))
-                .build());
+            (TransferData)
+                resource
+                    .getTransferData()
+                    .copyConstantFieldsToBuilder()
+                    .setTransferStatus(transferStatus)
+                    .setPendingTransferExpirationTime(checkNotNull(now))
+                    .build());
   }
 
   /**
@@ -171,7 +175,7 @@ public final class ResourceTransferUtils {
    */
   public static <
           R extends EppResource & ResourceWithTransferData,
-          B extends EppResource.Builder<R, B> & BuilderWithTransferData<B>>
+          B extends EppResource.Builder<R, B> & BuilderWithTransferData<TransferData, B>>
       R approvePendingTransfer(R resource, TransferStatus transferStatus, DateTime now) {
     checkArgument(transferStatus.isApproved(), "Not an approval transfer status");
     B builder = resolvePendingTransfer(resource, transferStatus, now);

core/src/main/java/google/registry/model/contact/ContactResource.java

@@ -30,7 +30,7 @@ import google.registry.model.EppResource.ResourceWithTransferData;
 import google.registry.model.annotations.ExternalMessagingName;
 import google.registry.model.annotations.ReportedOn;
 import google.registry.model.contact.PostalInfo.Type;
-import google.registry.model.transfer.TransferData;
+import google.registry.model.transfer.ContactTransferData;
 import google.registry.persistence.VKey;
 import google.registry.persistence.WithStringVKey;
 import google.registry.schema.replay.DatastoreAndSqlEntity;
@@ -170,7 +170,7 @@ public class ContactResource extends EppResource
   ContactAuthInfo authInfo;
 
   /** Data about any pending or past transfers on this contact. */
-  TransferData transferData;
+  ContactTransferData transferData;
 
   /**
    * The time that this resource was last transferred.
@@ -242,8 +242,8 @@ public class ContactResource extends EppResource
   }
 
   @Override
-  public final TransferData getTransferData() {
-    return Optional.ofNullable(transferData).orElse(TransferData.EMPTY);
+  public final ContactTransferData getTransferData() {
+    return Optional.ofNullable(transferData).orElse(ContactTransferData.EMPTY);
   }
 
   @Override
@@ -285,7 +285,7 @@ public class ContactResource extends EppResource
 
   /** A builder for constructing {@link ContactResource}, since it is immutable. */
   public static class Builder extends EppResource.Builder<ContactResource, Builder>
-      implements BuilderWithTransferData<Builder> {
+      implements BuilderWithTransferData<ContactTransferData, Builder> {
 
     public Builder() {}
 
@@ -350,7 +350,7 @@ public class ContactResource extends EppResource
     }
 
     @Override
-    public Builder setTransferData(TransferData transferData) {
+    public Builder setTransferData(ContactTransferData transferData) {
       getInstance().transferData = transferData;
       return this;
     }
@@ -380,7 +380,7 @@ public class ContactResource extends EppResource
     public ContactResource build() {
       ContactResource instance = getInstance();
       // If TransferData is totally empty, set it to null.
-      if (TransferData.EMPTY.equals(instance.transferData)) {
+      if (ContactTransferData.EMPTY.equals(instance.transferData)) {
         setTransferData(null);
       }
       // Set the searchName using the internationalized and localized postal info names.

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

@@ -63,7 +63,7 @@ import google.registry.model.eppcommon.StatusValue;
 import google.registry.model.host.HostResource;
 import google.registry.model.poll.PollMessage;
 import google.registry.model.registry.Registry;
-import google.registry.model.transfer.TransferData;
+import google.registry.model.transfer.DomainTransferData;
 import google.registry.model.transfer.TransferStatus;
 import google.registry.persistence.VKey;
 import google.registry.persistence.WithStringVKey;
@@ -110,7 +110,9 @@ import org.joda.time.Interval;
 @WithStringVKey
 @ExternalMessagingName("domain")
 public class DomainBase extends EppResource
-    implements DatastoreAndSqlEntity, ForeignKeyedEppResource, ResourceWithTransferData {
+    implements DatastoreAndSqlEntity,
+        ForeignKeyedEppResource,
+        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;
@@ -253,7 +255,7 @@ public class DomainBase extends EppResource
   String smdId;
 
   /** Data about any pending or past transfers on this domain. */
-  TransferData transferData;
+  DomainTransferData transferData;
 
   /**
    * The time that this resource was last transferred.
@@ -322,8 +324,8 @@ public class DomainBase extends EppResource
   }
 
   @Override
-  public TransferData getTransferData() {
-    return Optional.ofNullable(transferData).orElse(TransferData.EMPTY);
+  public DomainTransferData getTransferData() {
+    return Optional.ofNullable(transferData).orElse(DomainTransferData.EMPTY);
   }
 
   @Override
@@ -402,7 +404,7 @@ public class DomainBase extends EppResource
   @Override
   public DomainBase cloneProjectedAtTime(final DateTime now) {
 
-    TransferData transferData = getTransferData();
+    DomainTransferData transferData = getTransferData();
     DateTime transferExpirationTime = transferData.getPendingTransferExpirationTime();
 
     // If there's a pending transfer that has expired, handle it.
@@ -644,7 +646,7 @@ public class DomainBase extends EppResource
 
   /** A builder for constructing {@link DomainBase}, since it is immutable. */
   public static class Builder extends EppResource.Builder<DomainBase, Builder>
-      implements BuilderWithTransferData<Builder> {
+      implements BuilderWithTransferData<DomainTransferData, Builder> {
 
     public Builder() {}
 
@@ -656,7 +658,7 @@ public class DomainBase extends EppResource
     public DomainBase build() {
       DomainBase instance = getInstance();
       // If TransferData is totally empty, set it to null.
-      if (TransferData.EMPTY.equals(getInstance().transferData)) {
+      if (DomainTransferData.EMPTY.equals(getInstance().transferData)) {
         setTransferData(null);
       }
       // A DomainBase has status INACTIVE if there are no nameservers.
@@ -830,7 +832,7 @@ public class DomainBase extends EppResource
     }
 
     @Override
-    public Builder setTransferData(TransferData transferData) {
+    public Builder setTransferData(DomainTransferData transferData) {
       getInstance().transferData = transferData;
       return thisCastToDerived();
     }

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

@@ -121,5 +121,10 @@ public abstract class BaseTransferObject extends ImmutableObject {
       getInstance().pendingTransferExpirationTime = pendingTransferExpirationTime;
       return thisCastToDerived();
     }
+
+    @Override
+    public T build() {
+      return super.build();
+    }
   }
 }

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

@@ -0,0 +1,48 @@
+// 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.model.transfer;
+
+import com.googlecode.objectify.annotation.Embed;
+import com.googlecode.objectify.annotation.Unindex;
+import javax.persistence.Embeddable;
+
+/** Transfer data for contact. */
+@Embed
+@Unindex
+@Embeddable
+public class ContactTransferData extends TransferData<ContactTransferData.Builder> {
+  public static final ContactTransferData EMPTY = new ContactTransferData();
+
+  @Override
+  public boolean isEmpty() {
+    return EMPTY.equals(this);
+  }
+
+  @Override
+  public Builder asBuilder() {
+    return new Builder(clone(this));
+  }
+
+  public static class Builder
+      extends TransferData.Builder<ContactTransferData, ContactTransferData.Builder> {
+    /** Create a {@link ContactTransferData.Builder} wrapping a new instance. */
+    public Builder() {}
+
+    /** Create a {@link ContactTransferData.Builder} wrapping the given instance. */
+    private Builder(ContactTransferData instance) {
+      super(instance);
+    }
+  }
+}

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

@@ -0,0 +1,186 @@
+// 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.model.transfer;
+
+import com.googlecode.objectify.annotation.Embed;
+import com.googlecode.objectify.annotation.Ignore;
+import com.googlecode.objectify.annotation.IgnoreSave;
+import com.googlecode.objectify.annotation.Unindex;
+import com.googlecode.objectify.condition.IfNull;
+import google.registry.model.billing.BillingEvent;
+import google.registry.model.domain.Period;
+import google.registry.model.domain.Period.Unit;
+import google.registry.model.poll.PollMessage;
+import google.registry.persistence.VKey;
+import javax.annotation.Nullable;
+import javax.persistence.AttributeOverride;
+import javax.persistence.AttributeOverrides;
+import javax.persistence.Column;
+import javax.persistence.Embeddable;
+import javax.persistence.Embedded;
+import org.joda.time.DateTime;
+
+/** Transfer data for domain. */
+@Embed
+@Unindex
+@Embeddable
+public class DomainTransferData extends TransferData<DomainTransferData.Builder> {
+  public static final DomainTransferData EMPTY = new DomainTransferData();
+
+  /**
+   * The period to extend the registration upon completion of the transfer.
+   *
+   * <p>By default, domain transfers are for one year. This can be changed to zero by using the
+   * superuser EPP extension.
+   */
+  @Embedded
+  @AttributeOverrides({
+    @AttributeOverride(name = "unit", column = @Column(name = "transfer_renew_period_unit")),
+    @AttributeOverride(name = "value", column = @Column(name = "transfer_renew_period_value"))
+  })
+  Period transferPeriod = Period.create(1, Unit.YEARS);
+
+  /**
+   * The registration expiration time resulting from the approval - speculative or actual - of the
+   * most recent transfer request, applicable for domains only.
+   *
+   * <p>For pending transfers, this is the expiration time that will take effect under a projected
+   * server approval. For approved transfers, this is the actual expiration time of the domain as of
+   * the moment of transfer completion. For rejected or cancelled transfers, this field will be
+   * reset to null.
+   *
+   * <p>Note that even when this field is set, it does not necessarily mean that the post-transfer
+   * domain has a new expiration time. Superuser transfers may not include a bundled 1 year renewal
+   * at all, or even when a renewal is bundled, for a transfer during the autorenew grace period the
+   * bundled renewal simply subsumes the recent autorenewal, resulting in the same expiration time.
+   */
+  // TODO(b/36405140): backfill this field for existing domains to which it should apply.
+  @Column(name = "transfer_registration_expiration_time")
+  DateTime transferredRegistrationExpirationTime;
+
+  @Ignore
+  @Column(name = "transfer_billing_cancellation_id")
+  Long billingCancellationId;
+
+  /**
+   * The regular one-time billing event that will be charged for a server-approved transfer.
+   *
+   * <p>This field should be null if there is not currently a pending transfer or if the object
+   * being transferred is not a domain.
+   *
+   * <p>TODO(b/158230654) Remove unused columns for TransferData in Contact table.
+   */
+  @IgnoreSave(IfNull.class)
+  @Column(name = "transfer_billing_event_id")
+  VKey<BillingEvent.OneTime> serverApproveBillingEvent;
+
+  /**
+   * The autorenew billing event that should be associated with this resource after the transfer.
+   *
+   * <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")
+  VKey<BillingEvent.Recurring> serverApproveAutorenewEvent;
+
+  /**
+   * The autorenew poll message that should be associated with this resource after the transfer.
+   *
+   * <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_autorenew_poll_message_id")
+  VKey<PollMessage.Autorenew> serverApproveAutorenewPollMessage;
+
+  @Override
+  public Builder copyConstantFieldsToBuilder() {
+    return super.copyConstantFieldsToBuilder().setTransferPeriod(this.transferPeriod);
+  }
+
+  public Period getTransferPeriod() {
+    return transferPeriod;
+  }
+
+  @Nullable
+  public DateTime getTransferredRegistrationExpirationTime() {
+    return transferredRegistrationExpirationTime;
+  }
+
+  @Nullable
+  public VKey<BillingEvent.OneTime> getServerApproveBillingEvent() {
+    return serverApproveBillingEvent;
+  }
+
+  @Nullable
+  public VKey<BillingEvent.Recurring> getServerApproveAutorenewEvent() {
+    return serverApproveAutorenewEvent;
+  }
+
+  @Nullable
+  public VKey<PollMessage.Autorenew> getServerApproveAutorenewPollMessage() {
+    return serverApproveAutorenewPollMessage;
+  }
+
+  @Override
+  public boolean isEmpty() {
+    return EMPTY.equals(this);
+  }
+
+  @Override
+  public Builder asBuilder() {
+    return new Builder(clone(this));
+  }
+
+  public static class Builder extends TransferData.Builder<DomainTransferData, Builder> {
+    /** Create a {@link DomainTransferData.Builder} wrapping a new instance. */
+    public Builder() {}
+
+    /** Create a {@link Builder} wrapping the given instance. */
+    private Builder(DomainTransferData instance) {
+      super(instance);
+    }
+
+    public Builder setTransferPeriod(Period transferPeriod) {
+      getInstance().transferPeriod = transferPeriod;
+      return this;
+    }
+
+    public Builder setTransferredRegistrationExpirationTime(
+        DateTime transferredRegistrationExpirationTime) {
+      getInstance().transferredRegistrationExpirationTime = transferredRegistrationExpirationTime;
+      return this;
+    }
+
+    public Builder setServerApproveBillingEvent(
+        VKey<BillingEvent.OneTime> serverApproveBillingEvent) {
+      getInstance().serverApproveBillingEvent = serverApproveBillingEvent;
+      return this;
+    }
+
+    public Builder setServerApproveAutorenewEvent(
+        VKey<BillingEvent.Recurring> serverApproveAutorenewEvent) {
+      getInstance().serverApproveAutorenewEvent = serverApproveAutorenewEvent;
+      return this;
+    }
+
+    public Builder setServerApproveAutorenewPollMessage(
+        VKey<PollMessage.Autorenew> serverApproveAutorenewPollMessage) {
+      getInstance().serverApproveAutorenewPollMessage = serverApproveAutorenewPollMessage;
+      return this;
+    }
+  }
+}

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

@@ -17,38 +17,31 @@ package google.registry.model.transfer;
 import static google.registry.util.CollectionUtils.nullToEmptyImmutableCopy;
 
 import com.google.common.collect.ImmutableSet;
-import com.googlecode.objectify.annotation.Embed;
 import com.googlecode.objectify.annotation.Ignore;
 import com.googlecode.objectify.annotation.IgnoreSave;
-import com.googlecode.objectify.annotation.Unindex;
 import com.googlecode.objectify.condition.IfNull;
 import google.registry.model.Buildable;
 import google.registry.model.EppResource;
-import google.registry.model.billing.BillingEvent;
-import google.registry.model.domain.Period;
-import google.registry.model.domain.Period.Unit;
 import google.registry.model.eppcommon.Trid;
-import google.registry.model.poll.PollMessage;
 import google.registry.persistence.VKey;
+import google.registry.util.TypeUtils.TypeInstantiator;
 import java.util.Set;
 import javax.annotation.Nullable;
 import javax.persistence.AttributeOverride;
 import javax.persistence.AttributeOverrides;
 import javax.persistence.Column;
 import javax.persistence.Embedded;
+import javax.persistence.MappedSuperclass;
 import javax.persistence.Transient;
-import org.joda.time.DateTime;
 
 /**
  * Common transfer data for {@link EppResource} types. Only applies to domains and contacts; hosts
  * are implicitly transferred with their superordinate domain.
  */
-@Embed
-@Unindex
-@javax.persistence.Embeddable
-public class TransferData extends BaseTransferObject implements Buildable {
-
-  public static final TransferData EMPTY = new TransferData();
+@MappedSuperclass
+public abstract class TransferData<
+        B extends TransferData.Builder<? extends TransferData, ? extends TransferData.Builder>>
+    extends BaseTransferObject implements Buildable {
 
   /** The transaction id of the most recent transfer request (or null if there never was one). */
   @Embedded
@@ -62,37 +55,6 @@ public class TransferData extends BaseTransferObject implements Buildable {
   })
   Trid transferRequestTrid;
 
-  /**
-   * The period to extend the registration upon completion of the transfer.
-   *
-   * <p>By default, domain transfers are for one year. This can be changed to zero by using the
-   * superuser EPP extension.
-   */
-  @Embedded
-  @AttributeOverrides({
-    @AttributeOverride(name = "unit", column = @Column(name = "transfer_renew_period_unit")),
-    @AttributeOverride(name = "value", column = @Column(name = "transfer_renew_period_value"))
-  })
-  Period transferPeriod = Period.create(1, Unit.YEARS);
-
-  /**
-   * The registration expiration time resulting from the approval - speculative or actual - of the
-   * most recent transfer request, applicable for domains only.
-   *
-   * <p>For pending transfers, this is the expiration time that will take effect under a projected
-   * server approval. For approved transfers, this is the actual expiration time of the domain as of
-   * the moment of transfer completion. For rejected or cancelled transfers, this field will be
-   * reset to null.
-   *
-   * <p>Note that even when this field is set, it does not necessarily mean that the post-transfer
-   * domain has a new expiration time. Superuser transfers may not include a bundled 1 year renewal
-   * at all, or even when a renewal is bundled, for a transfer during the autorenew grace period the
-   * bundled renewal simply subsumes the recent autorenewal, resulting in the same expiration time.
-   */
-  // TODO(b/36405140): backfill this field for existing domains to which it should apply.
-  @Column(name = "transfer_registration_expiration_time")
-  DateTime transferredRegistrationExpirationTime;
-
   /**
    * The billing event and poll messages associated with a server-approved transfer.
    *
@@ -116,85 +78,26 @@ public class TransferData extends BaseTransferObject implements Buildable {
   @Column(name = "transfer_losing_poll_message_id")
   Long losingTransferPollMessageId;
 
-  @Ignore
-  @Column(name = "transfer_billing_cancellation_id")
-  Long billingCancellationId;
-
-  /**
-   * The regular one-time billing event that will be charged for a server-approved transfer.
-   *
-   * <p>This field should be null if there is not currently a pending transfer or if the object
-   * being transferred is not a domain.
-   *
-   * <p>TODO(b/158230654) Remove unused columns for TransferData in Contact table.
-   */
-  @IgnoreSave(IfNull.class)
-  @Column(name = "transfer_billing_event_id")
-  VKey<BillingEvent.OneTime> serverApproveBillingEvent;
-
-  /**
-   * The autorenew billing event that should be associated with this resource after the transfer.
-   *
-   * <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")
-  VKey<BillingEvent.Recurring> serverApproveAutorenewEvent;
-
-  /**
-   * The autorenew poll message that should be associated with this resource after the transfer.
-   *
-   * <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_autorenew_poll_message_id")
-  VKey<PollMessage.Autorenew> serverApproveAutorenewPollMessage;
+  public abstract boolean isEmpty();
 
   @Nullable
   public Trid getTransferRequestTrid() {
     return transferRequestTrid;
   }
 
-  public Period getTransferPeriod() {
-    return transferPeriod;
-  }
-
-  @Nullable
-  public DateTime getTransferredRegistrationExpirationTime() {
-    return transferredRegistrationExpirationTime;
-  }
-
   public ImmutableSet<VKey<? extends TransferServerApproveEntity>> getServerApproveEntities() {
     return nullToEmptyImmutableCopy(serverApproveEntities);
   }
 
-  @Nullable
-  public VKey<BillingEvent.OneTime> getServerApproveBillingEvent() {
-    return serverApproveBillingEvent;
-  }
-
-  @Nullable
-  public VKey<BillingEvent.Recurring> getServerApproveAutorenewEvent() {
-    return serverApproveAutorenewEvent;
-  }
-
-  @Nullable
-  public VKey<PollMessage.Autorenew> getServerApproveAutorenewPollMessage() {
-    return serverApproveAutorenewPollMessage;
-  }
-
   @Override
-  public Builder asBuilder() {
-    return new Builder(clone(this));
-  }
+  public abstract Builder asBuilder();
 
   /**
    * Returns a fresh Builder populated only with the constant fields of this TransferData, i.e.
    * those that are fixed and unchanging throughout the transfer process.
    *
    * <p>These fields are:
+   *
    * <ul>
    *   <li>transferRequestTrid
    *   <li>transferRequestTime
@@ -203,64 +106,43 @@ public class TransferData extends BaseTransferObject implements Buildable {
    *   <li>transferPeriod
    * </ul>
    */
-  public Builder copyConstantFieldsToBuilder() {
-    return new Builder()
+  public B copyConstantFieldsToBuilder() {
+    B newBuilder = new TypeInstantiator<B>(getClass()) {}.instantiate();
+    newBuilder
+        // .setTransferPeriod(this.transferPeriod)
         .setTransferRequestTrid(this.transferRequestTrid)
         .setTransferRequestTime(this.transferRequestTime)
         .setGainingClientId(this.gainingClientId)
-        .setLosingClientId(this.losingClientId)
-        .setTransferPeriod(this.transferPeriod);
+        .setLosingClientId(this.losingClientId);
+    return newBuilder;
   }
 
   /** Builder for {@link TransferData} because it is immutable. */
-  public static class Builder extends BaseTransferObject.Builder<TransferData, Builder> {
+  public abstract static class Builder<T extends TransferData, B extends Builder<T, B>>
+      extends BaseTransferObject.Builder<T, B> {
 
     /** Create a {@link Builder} wrapping a new instance. */
     public Builder() {}
 
     /** Create a {@link Builder} wrapping the given instance. */
-    private Builder(TransferData instance) {
+    protected Builder(T instance) {
       super(instance);
     }
 
-    public Builder setTransferRequestTrid(Trid transferRequestTrid) {
+    public B setTransferRequestTrid(Trid transferRequestTrid) {
       getInstance().transferRequestTrid = transferRequestTrid;
-      return this;
+      return thisCastToDerived();
     }
 
-    public Builder setTransferPeriod(Period transferPeriod) {
-      getInstance().transferPeriod = transferPeriod;
-      return this;
-    }
-
-    public Builder setTransferredRegistrationExpirationTime(
-        DateTime transferredRegistrationExpirationTime) {
-      getInstance().transferredRegistrationExpirationTime = transferredRegistrationExpirationTime;
-      return this;
-    }
-
-    public Builder setServerApproveEntities(
+    public B setServerApproveEntities(
         ImmutableSet<VKey<? extends TransferServerApproveEntity>> serverApproveEntities) {
       getInstance().serverApproveEntities = serverApproveEntities;
-      return this;
+      return thisCastToDerived();
     }
 
-    public Builder setServerApproveBillingEvent(
-        VKey<BillingEvent.OneTime> serverApproveBillingEvent) {
-      getInstance().serverApproveBillingEvent = serverApproveBillingEvent;
-      return this;
-    }
-
-    public Builder setServerApproveAutorenewEvent(
-        VKey<BillingEvent.Recurring> serverApproveAutorenewEvent) {
-      getInstance().serverApproveAutorenewEvent = serverApproveAutorenewEvent;
-      return this;
-    }
-
-    public Builder setServerApproveAutorenewPollMessage(
-        VKey<PollMessage.Autorenew> serverApproveAutorenewPollMessage) {
-      getInstance().serverApproveAutorenewPollMessage = serverApproveAutorenewPollMessage;
-      return this;
+    @Override
+    public T build() {
+      return super.build();
     }
   }
 

core/src/main/java/google/registry/rde/ContactResourceToXjcConverter.java

@@ -36,7 +36,6 @@ import google.registry.xjc.eppcom.XjcEppcomTrStatusType;
 import google.registry.xjc.rdecontact.XjcRdeContact;
 import google.registry.xjc.rdecontact.XjcRdeContactElement;
 import google.registry.xjc.rdecontact.XjcRdeContactTransferDataType;
-import java.util.Objects;
 import javax.annotation.CheckForNull;
 import javax.annotation.Nullable;
 
@@ -102,7 +101,7 @@ final class ContactResourceToXjcConverter {
     //       required before an automated response action will be taken by
     //       the registry.  For all other status types, the value identifies
     //       the date and time when the request was completed.
-    if (!Objects.equals(model.getTransferData(), TransferData.EMPTY)) {
+    if (!model.getTransferData().isEmpty()) {
       bean.setTrnData(convertTransferData(model.getTransferData()));
     }
 

core/src/main/java/google/registry/rde/DomainBaseToXjcConverter.java

@@ -28,6 +28,7 @@ import google.registry.model.domain.rgp.GracePeriodStatus;
 import google.registry.model.domain.secdns.DelegationSignerData;
 import google.registry.model.eppcommon.StatusValue;
 import google.registry.model.rde.RdeMode;
+import google.registry.model.transfer.DomainTransferData;
 import google.registry.model.transfer.TransferData;
 import google.registry.persistence.VKey;
 import google.registry.util.Idn;
@@ -234,7 +235,7 @@ final class DomainBaseToXjcConverter {
         //    *  An OPTIONAL <exDate> element that contains the end of the
         //       domain name object's validity period (expiry date) if the
         //       transfer caused or causes a change in the validity period.
-        if (!model.getTransferData().equals(TransferData.EMPTY)) {
+        if (!model.getTransferData().isEmpty()) {
           // Temporary check to make sure that there really was a transfer. A bug caused spurious
           // empty transfer records to get generated for deleted domains.
           // TODO(b/33289763): remove the hasGainingAndLosingRegistrars check in February 2017
@@ -258,7 +259,7 @@ final class DomainBaseToXjcConverter {
   }
 
   /** Converts {@link TransferData} to {@link XjcRdeDomainTransferDataType}. */
-  private static XjcRdeDomainTransferDataType convertTransferData(TransferData model) {
+  private static XjcRdeDomainTransferDataType convertTransferData(DomainTransferData model) {
     XjcRdeDomainTransferDataType bean = new XjcRdeDomainTransferDataType();
     bean.setTrStatus(
         XjcEppcomTrStatusType.fromValue(model.getTransferStatus().getXmlName()));