Symfony\Component\HttpFoundation\Request::getAcceptableContentTypes PHP Method

    public function getAcceptableContentTypes()
    {
        if (null !== $this->acceptableContentTypes) {
            return $this->acceptableContentTypes;
        }

        return $this->acceptableContentTypes = array_keys(AcceptHeader::fromString($this->headers->get('Accept'))->all());
    }

 /**
  * @return bool
  */
 private function shouldHandleRequest()
 {
     if ($this->handleNonJsonRequests) {
         return true;
     }
     return in_array('application/json', $this->request->getAcceptableContentTypes());
 }