Add extra flow logic hook for domain allocation

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=138679232

java/google/registry/flows/domain/DomainAllocateFlow.java

@@ -37,6 +37,7 @@ import static google.registry.util.CollectionUtils.isNullOrEmpty;
 import static google.registry.util.DateTimeUtils.END_OF_TIME;
 import static google.registry.util.DateTimeUtils.leapSafeAddYears;
 
+import com.google.common.base.Optional;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.net.InternetDomainName;
@@ -175,6 +176,7 @@ public class DomainAllocateFlow implements TransactionalFlow {
         .setNameservers(command.getNameservers())
         .setContacts(command.getContacts())
         .build();
+    handleExtraFlowLogic(registry.getTldStr(), years, historyEntry, newDomain, now);
     entitiesToSave.add(
         newDomain,
         buildApplicationHistory(application, now),
@@ -360,6 +362,22 @@ public class DomainAllocateFlow implements TransactionalFlow {
         && !matchesAnchorTenantReservation(domainName, authInfoToken);
   }
 
+  private void handleExtraFlowLogic(
+      String tld, int years, HistoryEntry historyEntry, DomainResource newDomain, DateTime now)
+          throws EppException {
+    Optional<RegistryExtraFlowLogic> extraFlowLogic =
+        RegistryExtraFlowLogicProxy.newInstanceForTld(tld);
+    if (extraFlowLogic.isPresent()) {
+      extraFlowLogic.get().performAdditionalDomainAllocateLogic(
+          newDomain,
+          clientId,
+          now,
+          years,
+          eppInput,
+          historyEntry);
+    }
+  }
+
   private void enqueueTasks(AllocateCreateExtension allocateCreate, DomainResource newDomain) {
     if (newDomain.shouldPublishToDns()) {
       DnsQueue.create().addDomainRefreshTask(newDomain.getFullyQualifiedDomainName());

java/google/registry/flows/domain/RegistryExtraFlowLogic.java

@@ -69,6 +69,15 @@ public interface RegistryExtraFlowLogic {
       EppInput eppInput,
       HistoryEntry historyEntry) throws EppException;
 
+  /** Performs additional tasks required for an allocate command. */
+  public void performAdditionalDomainAllocateLogic(
+      DomainResource domain,
+      String clientId,
+      DateTime asOfDate,
+      int years,
+      EppInput eppInput,
+      HistoryEntry historyEntry) throws EppException;
+
   /** Computes the expected creation fee. */
   public BaseFee getCreateFeeOrCredit(
       String domainName,