Propogate onChange() event when getFooBuilder() is on an oneof message

field.

Change-Id: Idb5b53da5accd24038a895aba49b684eeee95814

java/src/test/java/com/google/protobuf/GeneratedMessageTest.java

@@ -56,9 +56,10 @@ import protobuf_unittest.UnittestProto;
 import protobuf_unittest.UnittestProto.ForeignEnum;
 import protobuf_unittest.UnittestProto.ForeignMessage;
 import protobuf_unittest.UnittestProto.ForeignMessageOrBuilder;
+import protobuf_unittest.UnittestProto.NestedTestAllTypes;
 import protobuf_unittest.UnittestProto.TestAllExtensions;
-import protobuf_unittest.UnittestProto.TestAllTypes;
 import protobuf_unittest.UnittestProto.TestAllTypes.NestedMessage;
+import protobuf_unittest.UnittestProto.TestAllTypes;
 import protobuf_unittest.UnittestProto.TestAllTypesOrBuilder;
 import protobuf_unittest.UnittestProto.TestExtremeDefaultValues;
 import protobuf_unittest.UnittestProto.TestOneof2;
@@ -1510,6 +1511,17 @@ public class GeneratedMessageTest extends TestCase {
     }
   }
 
+  public void testOneofNestedBuilderOnChangePropagation() {
+    NestedTestAllTypes.Builder parentBuilder = NestedTestAllTypes.newBuilder();
+    TestAllTypes.Builder builder = parentBuilder.getPayloadBuilder();
+    builder.getOneofNestedMessageBuilder();
+    assertTrue(builder.hasOneofNestedMessage());
+    assertTrue(parentBuilder.hasPayload());
+    NestedTestAllTypes message = parentBuilder.build();
+    assertTrue(message.hasPayload());
+    assertTrue(message.getPayload().hasOneofNestedMessage());
+  }
+
   public void testGetRepeatedFieldBuilder() {
     Descriptor descriptor = TestAllTypes.getDescriptor();
 

src/google/protobuf/compiler/java/java_message_field.cc

@@ -718,6 +718,7 @@ GenerateBuilderMembers(io::Printer* printer) const {
       "    $oneof_name$_ = null;\n"
       "  }\n"
       "  $set_oneof_case_message$;\n"
+      "  $on_changed$;\n"
       "  return $name$Builder_;\n"
       "}\n");
   }