unc, request)

            if response is not None:
                self._debug_log_completion(starting_time, response)
                return response
            elif ack.response is not None:
                self._debug_log_completion(starting_time, ack.response)
                return ack.response
        else:
            if listener.auto_acknowledgement:
                # acknowledge immediately in case of Events API
                ack()

            if not request.lazy_only:
                # start 