Fix NPE in GetHistoryEntriesCommand

The code was not checking the value returned by getTrid() to make sure it was
not null.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=172384499

java/google/registry/model/reporting/HistoryEntry.java

@@ -31,6 +31,7 @@ import google.registry.model.annotations.ReportedOn;
 import google.registry.model.domain.Period;
 import google.registry.model.eppcommon.Trid;
 import java.util.Set;
+import javax.annotation.Nullable;
 import org.joda.time.DateTime;
 
 /** A record of an EPP command that mutated a resource. */
@@ -121,8 +122,8 @@ public class HistoryEntry extends ImmutableObject implements Buildable {
    */
   String otherClientId;
 
-  /** Transaction id that made this change. */
-  Trid trid;
+  /** Transaction id that made this change, or null if the entry was not created by a flow. */
+  @Nullable Trid trid;
 
   /** Whether this change was created by a superuser. */
   boolean bySuperuser;
@@ -170,7 +171,8 @@ public class HistoryEntry extends ImmutableObject implements Buildable {
     return otherClientId;
   }
 
-  public Trid getTrid() {
+  /** Returns the TRID, which may be null if the entry was not created by a normal flow. */
+  @Nullable public Trid getTrid() {
     return trid;
   }
 

java/google/registry/tools/GetHistoryEntriesCommand.java

@@ -77,8 +77,8 @@ final class GetHistoryEntriesCommand implements RemoteApiCommand {
           "Client: %s\nTime: %s\nClient TRID: %s\nServer TRID: %s\n%s\n",
           entry.getClientId(),
           entry.getModificationTime(),
-          entry.getTrid().getClientTransactionId(),
-          entry.getTrid().getServerTransactionId(),
+          (entry.getTrid() == null) ? null : entry.getTrid().getClientTransactionId(),
+          (entry.getTrid() == null) ? null : entry.getTrid().getServerTransactionId(),
           entry.getXmlBytes() == null
               ? String.format("[no XML stored for %s]\n", entry.getType())
               : XmlTransformer.prettyPrint(entry.getXmlBytes()));

javatests/google/registry/tools/GetHistoryEntriesCommandTest.java

@@ -0,0 +1,83 @@
+// Copyright 2017 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.tools;
+
+import static google.registry.testing.DatastoreHelper.createTld;
+import static google.registry.testing.DatastoreHelper.persistActiveDomain;
+import static google.registry.testing.DatastoreHelper.persistResource;
+import static google.registry.testing.FullFieldsTestEntityHelper.makeHistoryEntry;
+
+import google.registry.model.domain.DomainResource;
+import google.registry.model.domain.Period;
+import google.registry.model.reporting.HistoryEntry;
+import google.registry.testing.FakeClock;
+import org.joda.time.DateTime;
+import org.junit.Before;
+import org.junit.Test;
+
+/** Unit tests for {@link GetClaimsListCommand}. */
+public class GetHistoryEntriesCommandTest extends CommandTestCase<GetHistoryEntriesCommand> {
+
+  private final FakeClock clock = new FakeClock(DateTime.parse("2000-01-01T00:00:00Z"));
+
+  private DomainResource domain;
+
+  @Before
+  public void setup() {
+    createTld("tld");
+    domain = persistActiveDomain("example.tld");
+  }
+
+  @Test
+  public void testSuccess_works() throws Exception {
+    persistResource(
+        makeHistoryEntry(
+            domain,
+            HistoryEntry.Type.DOMAIN_CREATE,
+            Period.create(1, Period.Unit.YEARS),
+            "created",
+            clock.nowUtc()));
+    runCommand("--id=example.tld", "--type=DOMAIN");
+    assertStdoutIs(
+        "Client: foo\n"
+            + "Time: 2000-01-01T00:00:00.000Z\n"
+            + "Client TRID: ABC-123\n"
+            + "Server TRID: server-trid\n"
+            + "<?xml version=\"1.0\" encoding=\"UTF-8\"?><xml/>\n"
+            + "\n");
+  }
+
+  @Test
+  public void testSuccess_noTrid() throws Exception {
+    persistResource(
+        makeHistoryEntry(
+                domain,
+                HistoryEntry.Type.DOMAIN_CREATE,
+                Period.create(1, Period.Unit.YEARS),
+                "created",
+                clock.nowUtc())
+            .asBuilder()
+            .setTrid(null)
+            .build());
+    runCommand("--id=example.tld", "--type=DOMAIN");
+    assertStdoutIs(
+        "Client: foo\n"
+            + "Time: 2000-01-01T00:00:00.000Z\n"
+            + "Client TRID: null\n"
+            + "Server TRID: null\n"
+            + "<?xml version=\"1.0\" encoding=\"UTF-8\"?><xml/>\n"
+            + "\n");
+  }
+}