/**
  * {@inheritdoc}
  */
 public function getState(Request $request)
 {
     $value = $request->get($this->getRequestField());
     if (isset($value) && $value !== '' && !is_array($value)) {
         $request->query->set($this->getRequestField(), [$value]);
     }
     return parent::getState($request);
 }