/**
  * @param null $state
  * @return array
  */
 protected function getCodeFields($state = null)
 {
     $fields = parent::getCodeFields($state);
     if ($this->popup) {
         $fields['display'] = 'popup';
     }
     return $fields;
 }
 /**
  * @param string $code
  * @return array
  */
 protected function getTokenFields($code)
 {
     return parent::getTokenFields($code) + ['grant_type' => 'authorization_code'];
 }