public function onRequestBeforeSend(Event $event)
    {
        if (!$this->queue) {
            throw new \OutOfBoundsException('Mock queue is empty');
        }

        $request = $event['request'];
        $this->received[] = $request;
        // Detach the filter from the client so it's a one-time use
        if ($this->temporary && count($this->queue) == 1 && $request->getClient()) {
            $request->getClient()->getEventDispatcher()->removeSubscriber($this);
        }
        $this->dequeue($request);
    }