/**
  * Autocomplete the label of an entity.
  *
  * @param \Symfony\Component\HttpFoundation\Request $request
  *   The request object that contains the typed tags.
  * @param string $target_type
  *   The ID of the target entity type.
  * @param string $selection_handler
  *   The plugin ID of the entity reference selection handler.
  * @param string $selection_settings
  *   The settings that will be passed to the selection handler.
  *
  * @return \Symfony\Component\HttpFoundation\JsonResponse
  *   The matched entity labels as a JSON response.
  */
 public function handleAutocomplete(Request $request, $target_type, $selection_handler, $selection_settings = '')
 {
     $matches = array();
     // Get the typed string from the URL, if it exists.
     if ($input = $request->query->get('q')) {
         $typed_string = Tags::explode($input);
         $typed_string = Unicode::strtolower(array_pop($typed_string));
         // Selection settings are passed in as an encoded serialized array.
         $selection_settings = $selection_settings ? unserialize(base64_decode($selection_settings)) : array();
         $matches = $this->matcher->getMatches($target_type, $selection_handler, $selection_settings, $typed_string);
     }
     return new JsonResponse($matches);
 }
 /**
  * Autocomplete the label of an entity.
  *
  * @param \Symfony\Component\HttpFoundation\Request $request
  *   The request object that contains the typed tags.
  * @param string $target_type
  *   The ID of the target entity type.
  * @param string $selection_handler
  *   The plugin ID of the entity reference selection handler.
  * @param string $selection_settings_key
  *   The hashed key of the key/value entry that holds the selection handler
  *   settings.
  *
  * @return \Symfony\Component\HttpFoundation\JsonResponse
  *   The matched entity labels as a JSON response.
  *
  * @throws \Symfony\Component\HttpKernel\Exception\AccessDeniedHttpException
  *   Thrown if the selection settings key is not found in the key/value store
  *   or if it does not match the stored data.
  */
 public function handleAutocomplete(Request $request, $target_type, $selection_handler, $selection_settings_key)
 {
     $matches = array();
     // Get the typed string from the URL, if it exists.
     if ($input = $request->query->get('q')) {
         $typed_string = Tags::explode($input);
         $typed_string = Unicode::strtolower(array_pop($typed_string));
         // Selection settings are passed in as a hashed key of a serialized array
         // stored in the key/value store.
         $selection_settings = $this->keyValue->get($selection_settings_key, FALSE);
         if ($selection_settings !== FALSE) {
             $selection_settings_hash = Crypt::hmacBase64(serialize($selection_settings) . $target_type . $selection_handler, Settings::getHashSalt());
             if ($selection_settings_hash !== $selection_settings_key) {
                 // Disallow access when the selection settings hash does not match the
                 // passed-in key.
                 throw new AccessDeniedHttpException('Invalid selection settings key.');
             }
         } else {
             // Disallow access when the selection settings key is not found in the
             // key/value store.
             throw new AccessDeniedHttpException();
         }
         $matches = $this->matcher->getMatches($target_type, $selection_handler, $selection_settings, $typed_string);
     }
     return new JsonResponse($matches);
 }