public function setRoutingKey($routingKey)
    {
        // we have to throw an exception, otherwise the new routing key will just be ignored
        if ($this->queueDeclared && $this->routingKey != $routingKey) {
            throw new \RuntimeException('AMQP Consumer can not use a new routing key: queue has already been declared');
        }
        $this->routingKey = $routingKey;

        return $this;
    }