Symfony\Component\HttpFoundation\Response::getProtocolVersion PHP Method

    public function getProtocolVersion()
    {
        return $this->version;
    }

 /**
  * Sending back a response to mongrel2 webserver.
  *
  * @param Request $request
  * @param Response $response
  */
 private function sendResponseToMongrel(Request $request, Response $response)
 {
     $response->prepare($request);
     // Map back our Symfony Response to a MongrelResponse.
     $mongrelResponse = new MongrelResponse($request->attributes->get('mongrel2_uuid'), [$request->attributes->get('mongrel2_listener')]);
     $mongrelResponse->setContent($response->getContent());
     $headers = $response->headers->all();
     foreach ($response->headers->getCookies() as $cookie) {
         $headers['Set-Cookie'][] = $cookie;
     }
     $mongrelResponse->setHeaders($headers);
     $mongrelResponse->setHttpVersion($response->getProtocolVersion());
     $mongrelResponse->setStatusCode($response->getStatusCode());
     $mongrelResponse->setReasonPhrase(Response::$statusTexts[$response->getStatusCode()]);
     $this->handler->sendResponse($mongrelResponse);
 }