Change transfer flow tests to assert on entire TransferData contents

This CL changes the domain and contact transfer flows to check the entire
TransferData on the post-transfer resource, rather than just spot-checking
certain fields.  This approach provides much better code coverage - in
particular, it checks that the non-request flows (approve, cancel, reject)
don't modify the fields that they shouldn't be modifying, and that they do
actually clear out the transfer server-approve entities fields written by
the transfer request flow.  It's slightly orthogonal, but I also added
testing that the server-approve entities fields are actually set in the
request flows, which was previously untested.

This is pre-work for introducing an exDate-storing field into TransferData,
by making it easier to test everywhere that exDate is set *and* unset only
in the correct places.

As part of this CL, I've introduced a TransferData.copyConstantFieldsToBuilder()
method that is like asBuilder() but instead of copying all the fields to the new
builder, it only copies the logically constant ones: losing/gaining client IDs,
the request time and TRID, and transferPeriod.  This is useful both in tests but
is also used in the resolvingPendingTransfer() helper that centralizes the core
transfer resolution logic (as of []  That method has its own tests,
and in the process I removed a bunch of crufty defunct TransferData tests.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=171053454

javatests/google/registry/flows/domain/DomainTransferApproveFlowTest.java

@@ -107,13 +107,19 @@ public class DomainTransferApproveFlowTest
     clock.advanceOneMilli();
   }
 
-  private void assertTransferApproved(DomainResource domain) {
+  private void assertTransferApproved(DomainResource domain, TransferData oldTransferData) {
     assertAboutDomains().that(domain)
-        .hasTransferStatus(TransferStatus.CLIENT_APPROVED).and()
         .hasCurrentSponsorClientId("NewRegistrar").and()
         .hasLastTransferTime(clock.nowUtc()).and()
-        .hasPendingTransferExpirationTime(clock.nowUtc()).and()
         .doesNotHaveStatusValue(StatusValue.PENDING_TRANSFER);
+    // The domain TransferData should reflect the approved transfer as we expect, with
+    // all the speculative server-approve fields nulled out.
+    assertThat(domain.getTransferData())
+        .isEqualTo(
+            oldTransferData.copyConstantFieldsToBuilder()
+                .setTransferStatus(TransferStatus.CLIENT_APPROVED)
+                .setPendingTransferExpirationTime(clock.nowUtc())
+                .build());
   }
 
   private void setEppLoader(String commandFilename) {
@@ -150,6 +156,7 @@ public class DomainTransferApproveFlowTest
       DateTime expectedExpirationTime) throws Exception {
     setEppLoader(commandFilename);
     Registry registry = Registry.get(tld);
+    domain = reloadResourceByForeignKey();
     // Make sure the implicit billing event is there; it will be deleted by the flow.
     // We also expect to see autorenew events for the gaining and losing registrars.
     assertBillingEventsForResource(
@@ -161,6 +168,7 @@ public class DomainTransferApproveFlowTest
     assertThat(getPollMessages(domain, "NewRegistrar", clock.nowUtc().plusMonths(1))).hasSize(1);
     assertThat(getPollMessages(domain, "TheRegistrar", clock.nowUtc().plusMonths(1))).hasSize(1);
     // Setup done; run the test.
+    TransferData originalTransferData = domain.getTransferData();
     assertTransactionalFlow(true);
     runFlowAssertResponse(readFile(expectedXmlFilename));
     // Transfer should have succeeded. Verify correct fields were set.
@@ -173,7 +181,7 @@ public class DomainTransferApproveFlowTest
         getOnlyHistoryEntryOfType(domain, DOMAIN_TRANSFER_APPROVE);
     assertAboutHistoryEntries().that(historyEntryTransferApproved)
         .hasOtherClientId("NewRegistrar");
-    assertTransferApproved(domain);
+    assertTransferApproved(domain, originalTransferData);
     assertAboutDomains().that(domain).hasRegistrationExpirationTime(expectedExpirationTime);
     assertThat(ofy().load().key(domain.getAutorenewBillingEvent()).now().getEventTime())
         .isEqualTo(expectedExpirationTime);
@@ -369,7 +377,7 @@ public class DomainTransferApproveFlowTest
 
   @Test
   public void testSuccess_autorenewBeforeTransfer() throws Exception {
-    DomainResource domain = reloadResourceByForeignKey();
+    domain = reloadResourceByForeignKey();
     DateTime oldExpirationTime = clock.nowUtc().minusDays(1);
     persistResource(domain.asBuilder()
         .setRegistrationExpirationTime(oldExpirationTime)
@@ -407,7 +415,7 @@ public class DomainTransferApproveFlowTest
   @Test
   public void testFailure_badDomainPassword() throws Exception {
     // Change the domain's password so it does not match the password in the file.
-    domain = persistResource(domain.asBuilder()
+    persistResource(domain.asBuilder()
         .setAuthInfo(DomainAuthInfo.create(PasswordAuth.create("badpassword")))
         .build());
     thrown.expect(BadAuthInfoForResourceException.class);
@@ -472,7 +480,7 @@ public class DomainTransferApproveFlowTest
 
   @Test
   public void testFailure_deletedDomain() throws Exception {
-    domain = persistResource(
+    persistResource(
         domain.asBuilder().setDeletionTime(clock.nowUtc().minusDays(1)).build());
     thrown.expect(ResourceDoesNotExistException.class,
         String.format("(%s)", getUniqueIdFromCommand()));
@@ -574,7 +582,7 @@ public class DomainTransferApproveFlowTest
 
   @Test
   public void testSuccess_superuserExtension_transferPeriodZero() throws Exception {
-    DomainResource domain = reloadResourceByForeignKey();
+    domain = reloadResourceByForeignKey();
     TransferData.Builder transferDataBuilder = domain.getTransferData().asBuilder();
     persistResource(
         domain