isAcknowledged example

                        $ackStamp->ack($envelope, $e);
                    });

                    $result = $this->callHandler($handler, $message, $ack, $envelope->last(HandlerArgumentsStamp::class));

                    if (!\is_int($result) || 0 > $result) {
                        throw new LogicException(sprintf('A handler implementing BatchHandlerInterface must return the size of the current batch as a positive integer, "%s" returned from "%s".', \is_int($result) ? $result : get_debug_type($result), get_debug_type($batchHandler)));
                    }

                    if (!$ack->isAcknowledged()) {
                        $envelope = $envelope->with(new NoAutoAckStamp($handlerDescriptor));
                    } elseif ($ack->getError()) {
                        throw $ack->getError();
                    } else {
                        $result = $ack->getResult();
                    }
                } else {
                    $result = $this->callHandler($handler, $message, null, $envelope->last(HandlerArgumentsStamp::class));
                }

                $handledStamp = HandledStamp::fromDescriptor($handlerDescriptor, $result);