@Test
public void messageWithEnum() {

  TestProtos.MessageWithEnum message =
      TestProtos.MessageWithEnum.newBuilder().setLetter(TestProtos.Letter.B).build();
  Function<Message, ?> getter = protobufPath(message.getDescriptorForType(), "$.letter");
  Object apply = getter.apply(message);
  assertThat(apply, is(TestProtos.Letter.B.getValueDescriptor()));
}