Neos\Flow\Http\Headers::getAll PHP Method

    public function getAll()
    {
        $fields = $this->fields;
        $cacheControlHeader = $this->getCacheControlHeader();
        if (!empty($cacheControlHeader)) {
            $fields['Cache-Control'] = [$cacheControlHeader];
        }
        return $fields;
    }

 /**
  * Sends a prepared request and returns the respective response.
  *
  * @param Request $request
  * @return Response
  * @api
  */
 public function sendRequest(Request $request)
 {
     foreach ($this->automaticRequestHeaders->getAll() as $name => $values) {
         $request->setHeader($name, $values);
     }
     $this->lastRequest = $request;
     $this->lastResponse = $this->requestEngine->sendRequest($request);
     return $this->lastResponse;
 }