private void verifyCallbacks(MockNettyMessageProcessor processor) throws Exception {
    assertNotNull("There is no MockNettyMessageProcessor in the channel", processor);
    for (ChannelWriteCallback callback : processor.writeCallbacksToVerify) {
      callback.compareWithFuture();
      if (callback.exception != null) {
        throw callback.exception;
      }
    }
  }
Verifies any callbacks queued in the {@code processor}.
@param processor the {@link MockNettyMessageProcessor} that contains the callbacks that need to be verified.
@throws Exception
ambry-rest/src/test/java/com/github/ambry/rest/NettyResponseChannelTest.java