Migrate plural DNS writers field to being the canonical one

After this point all data is migrated to use the new canonical
plural version, and subsequent code changes can be made that use
multiple writers.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=161673486

java/google/registry/model/registry/Registry.java

@@ -18,10 +18,10 @@ import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Predicates.equalTo;
 import static com.google.common.base.Predicates.not;
+import static com.google.common.collect.Iterables.getOnlyElement;
 import static google.registry.config.RegistryConfig.getSingletonCacheRefreshDuration;
 import static google.registry.model.common.EntityGroupRoot.getCrossTldKey;
 import static google.registry.model.ofy.ObjectifyService.ofy;
-import static google.registry.util.CollectionUtils.isNullOrEmpty;
 import static google.registry.util.CollectionUtils.nullToEmptyImmutableCopy;
 import static google.registry.util.DateTimeUtils.END_OF_TIME;
 import static google.registry.util.DateTimeUtils.START_OF_TIME;
@@ -290,8 +290,8 @@ public class Registry extends ImmutableObject implements Buildable {
 
   @OnLoad
   public void migrateDnsWriters() {
-    if (isNullOrEmpty(dnsWriters)) {
+    if (dnsWriter == null) {
-      dnsWriters = ImmutableSet.of(dnsWriter);
+      dnsWriter = getOnlyElement(dnsWriters);
     }
   }
 
@@ -613,7 +613,7 @@ public class Registry extends ImmutableObject implements Buildable {
 
   @Deprecated
   public String getDnsWriter() {
-    return dnsWriter;
+    return getOnlyElement(dnsWriters);
   }
 
   public ImmutableSet<String> getDnsWriters() {
@@ -702,13 +702,13 @@ public class Registry extends ImmutableObject implements Buildable {
       return this;
     }
 
-    public Builder setDnsWriter(String dnsWriter) {
+    public Builder setDnsWriters(ImmutableSet<String> dnsWriters) {
-      getInstance().dnsWriter = checkArgumentNotNull(dnsWriter);
+      checkArgument(dnsWriters.size() == 1, "Multiple DNS writers are not yet supported");
-      getInstance().dnsWriters = ImmutableSet.of(dnsWriter);
+      getInstance().dnsWriters = dnsWriters;
+      getInstance().dnsWriter = getOnlyElement(dnsWriters);
       return this;
     }
 
-
     public Builder setAddGracePeriodLength(Duration addGracePeriodLength) {
       checkArgument(addGracePeriodLength.isLongerThan(Duration.ZERO),
           "addGracePeriodLength must be non-zero");

java/google/registry/tools/CreateOrUpdateTldCommand.java

@@ -393,7 +393,7 @@ abstract class CreateOrUpdateTldCommand extends MutatingCommand {
               dnsWriterNames.contains(dnsWriter.get()),
               "The DNS writer '%s' doesn't exist",
               dnsWriter.get());
-          builder.setDnsWriter(dnsWriter.get());
+          builder.setDnsWriters(ImmutableSet.of(dnsWriter.get()));
       }
 
       if (lrpPeriod != null) {

javatests/google/registry/dns/PublishDnsUpdatesActionTest.java

@@ -63,7 +63,8 @@ public class PublishDnsUpdatesActionTest {
   public void setUp() throws Exception {
     inject.setStaticField(Ofy.class, "clock", clock);
     createTld("xn--q9jyb4c");
-    persistResource(Registry.get("xn--q9jyb4c").asBuilder().setDnsWriter("mock").build());
+    persistResource(
+        Registry.get("xn--q9jyb4c").asBuilder().setDnsWriters(ImmutableSet.of("mock")).build());
     DomainResource domain1 = persistActiveDomain("example.xn--q9jyb4c");
     persistActiveSubordinateHost("ns1.example.xn--q9jyb4c", domain1);
     persistActiveSubordinateHost("ns2.example.xn--q9jyb4c", domain1);

javatests/google/registry/model/registry/label/PremiumListUtilsTest.java

@@ -37,6 +37,7 @@ import static org.joda.time.Duration.standardMinutes;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableSet;
 import com.googlecode.objectify.Key;
 import com.googlecode.objectify.VoidWork;
 import google.registry.dns.writer.VoidDnsWriter;
@@ -98,7 +99,7 @@ public class PremiumListUtilsTest {
         new Registry.Builder()
             .setTldStr("ghost")
             .setPremiumPricingEngine(StaticPremiumListPricingEngine.NAME)
-            .setDnsWriter(VoidDnsWriter.NAME)
+            .setDnsWriters(ImmutableSet.of(VoidDnsWriter.NAME))
             .build());
     assertThat(Registry.get("ghost").getPremiumList()).isNull();
     assertThat(getPremiumPrice("blah", Registry.get("ghost"))).isAbsent();

javatests/google/registry/testing/DatastoreHelper.java

@@ -268,7 +268,7 @@ public class DatastoreHelper {
         // Always set a default premium list. Tests that don't want it can delete it.
         .setPremiumList(persistPremiumList(tld, DEFAULT_PREMIUM_LIST_CONTENTS.get()))
         .setPremiumPricingEngine(StaticPremiumListPricingEngine.NAME)
-        .setDnsWriter(VoidDnsWriter.NAME)
+        .setDnsWriters(ImmutableSet.of(VoidDnsWriter.NAME))
         .build();
   }
 

javatests/google/registry/tools/CreateTldCommandTest.java

@@ -66,7 +66,7 @@ public class CreateTldCommandTest extends CommandTestCase<CreateTldCommand> {
     assertThat(registry.getAddGracePeriodLength()).isEqualTo(Registry.DEFAULT_ADD_GRACE_PERIOD);
     assertThat(registry.getCreationTime()).isIn(Range.closed(before, after));
     assertThat(registry.getDomainCreateRestricted()).isFalse();
-    assertThat(registry.getDnsWriter()).isEqualTo("FooDnsWriter");
+    assertThat(registry.getDnsWriters()).containsExactly("FooDnsWriter");
     assertThat(registry.getTldState(registry.getCreationTime())).isEqualTo(TldState.PREDELEGATION);
     assertThat(registry.getRedemptionGracePeriodLength())
         .isEqualTo(Registry.DEFAULT_REDEMPTION_GRACE_PERIOD);