Create a converter for sets of InetAddresses and use it in HostResource (#612)

* Create a converter for sets of inetAddresses and use it in HostResource

This can just be a set of strings where each string represents an
address;  there's no need for it to be a separate table. This allows
for simplification of the SQL schema.

* Regenerate golden SQL file after renaming v28 -> v29

* Add more tests and rename a typo in the file

* Refactor common test code and use tm methods

* Use JUnit5 API

* Rename test entity

core/src/test/java/google/registry/persistence/converter/InetAddressSetConverterTest.java

@@ -0,0 +1,86 @@
+// 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.converter;
+
+import static com.google.common.truth.Truth.assertThat;
+import static google.registry.persistence.transaction.TransactionManagerFactory.jpaTm;
+
+import com.google.common.collect.ImmutableSet;
+import com.google.common.net.InetAddresses;
+import google.registry.model.ImmutableObject;
+import google.registry.persistence.VKey;
+import google.registry.schema.replay.EntityTest.EntityForTesting;
+import google.registry.testing.AppEngineRule;
+import java.net.InetAddress;
+import java.util.Set;
+import javax.annotation.Nullable;
+import javax.persistence.Entity;
+import javax.persistence.Id;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+/** Unit tests for {@link google.registry.persistence.converter.InetAddressSetConverter}. */
+public class InetAddressSetConverterTest {
+
+  @RegisterExtension
+  public final AppEngineRule appEngine =
+      AppEngineRule.builder()
+          .withDatastoreAndCloudSql()
+          .withJpaUnitTestEntities(InetAddressSetTestEntity.class)
+          .build();
+
+  @Test
+  public void roundTripConversion_returnsSameAddresses() {
+    verifySaveAndLoad(
+        ImmutableSet.of(
+            InetAddresses.forString("0.0.0.0"),
+            InetAddresses.forString("192.168.0.1"),
+            InetAddresses.forString("2001:41d0:1:a41e:0:0:0:1"),
+            InetAddresses.forString("2041:0:140F::875B:131B")));
+  }
+
+  @Test
+  public void roundTrip_emptySet() {
+    verifySaveAndLoad(ImmutableSet.of());
+  }
+
+  @Test
+  public void roundTrip_null() {
+    verifySaveAndLoad(null);
+  }
+
+  private void verifySaveAndLoad(@Nullable Set<InetAddress> inetAddresses) {
+    InetAddressSetTestEntity testEntity = new InetAddressSetTestEntity(inetAddresses);
+    jpaTm().transact(() -> jpaTm().saveNew(testEntity));
+    InetAddressSetTestEntity persisted =
+        jpaTm().transact(() -> jpaTm().load(VKey.createSql(InetAddressSetTestEntity.class, "id")));
+    assertThat(persisted.addresses).isEqualTo(inetAddresses);
+  }
+
+  @Entity(name = "TestEntity") // Override entity name to avoid the nested class reference.
+  @EntityForTesting
+  private static class InetAddressSetTestEntity extends ImmutableObject {
+
+    @Id String name = "id";
+
+    Set<InetAddress> addresses;
+
+    private InetAddressSetTestEntity() {}
+
+    private InetAddressSetTestEntity(Set<InetAddress> addresses) {
+      this.addresses = addresses;
+    }
+  }
+}