/**
  * Creates a new message to retry.
  *
  * @param EnvelopeInterface $envelope
  * @param int               $attempt
  * @param \Exception        $exception
  *
  * @return Message
  */
 protected function createRetryMessage(EnvelopeInterface $envelope, $attempt, \Exception $exception = null)
 {
     $headers = $envelope->getHeaders();
     $headers[RetryProcessor::PROPERTY_KEY] = $attempt;
     if ($exception) {
         $headers['x-exception'] = ['message' => $exception->getMessage(), 'type' => get_class($exception), 'file' => $exception->getFile(), 'line' => $exception->getLine()];
     }
     $properties = new MessageProperties([MessageProperties::KEY_CONTENT_TYPE => $envelope->getContentType(), MessageProperties::KEY_DELIVERY_MODE => $envelope->getDeliveryMode(), MessageProperties::KEY_HEADERS => $headers, MessageProperties::KEY_PRIORITY => $envelope->getPriority()]);
     return new Message($envelope->getBody(), $properties, $envelope->getDeliveryTag(), $envelope->getRoutingKey());
 }