Move the AllocationToken entity to the token subpackage

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=204485366

javatests/google/registry/model/domain/token/AllocationTokenTest.java

@@ -0,0 +1,83 @@
+// Copyright 2018 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.domain.token;
+
+import static com.google.common.truth.Truth.assertThat;
+import static com.google.common.truth.Truth8.assertThat;
+import static google.registry.model.ofy.ObjectifyService.ofy;
+import static google.registry.testing.DatastoreHelper.persistResource;
+import static google.registry.testing.JUnitBackports.assertThrows;
+
+import com.googlecode.objectify.Key;
+import google.registry.model.EntityTestCase;
+import google.registry.model.reporting.HistoryEntry;
+import org.joda.time.DateTime;
+import org.junit.Test;
+
+/** Unit tests for {@link AllocationToken}. */
+public class AllocationTokenTest extends EntityTestCase {
+
+  @Test
+  public void testPersistence() {
+    AllocationToken token =
+        persistResource(
+            new AllocationToken.Builder()
+                .setToken("abc123")
+                .setRedemptionHistoryEntry(Key.create(HistoryEntry.class, 1L))
+                .setCreationTime(DateTime.parse("2010-11-12T05:00:00Z"))
+                .build());
+    assertThat(ofy().load().entity(token).now()).isEqualTo(token);
+  }
+
+  @Test
+  public void testIndexing() throws Exception {
+    verifyIndexing(
+        new AllocationToken.Builder()
+            .setToken("abc123")
+            .setCreationTime(DateTime.parse("2010-11-12T05:00:00Z"))
+            .build(),
+        "token");
+  }
+
+  @Test
+  public void testCreationTime_autoPopulates() {
+    AllocationToken tokenBeforePersisting =
+        new AllocationToken.Builder().setToken("abc123").build();
+    assertThat(tokenBeforePersisting.getCreationTime()).isEmpty();
+    AllocationToken tokenAfterPersisting = persistResource(tokenBeforePersisting);
+    assertThat(tokenAfterPersisting.getCreationTime()).hasValue(clock.nowUtc());
+  }
+
+  @Test
+  public void testSetCreationTime_cantCallMoreThanOnce() {
+    AllocationToken.Builder builder =
+        new AllocationToken.Builder()
+            .setToken("foobar")
+            .setCreationTime(DateTime.parse("2010-11-12T05:00:00Z"));
+    IllegalStateException thrown =
+        assertThrows(
+            IllegalStateException.class,
+            () -> builder.setCreationTime(DateTime.parse("2010-11-13T05:00:00Z")));
+    assertThat(thrown).hasMessageThat().isEqualTo("creationTime can only be set once");
+  }
+
+  @Test
+  public void testSetToken_cantCallMoreThanOnce() {
+    AllocationToken.Builder builder = new AllocationToken.Builder().setToken("foobar");
+    IllegalStateException thrown =
+        assertThrows(IllegalStateException.class, () -> builder.setToken("barfoo"));
+    assertThat(thrown).hasMessageThat().isEqualTo("token can only be set once");
+  }
+}