public function retrieveAuthorizationCode($authorizationCode)
 {
     $data = Json::decode(Base64Url::decode($authorizationCode));
     return new AuthorizationCode($data['client_id'], $data['user_id'], $data['issued_at'], $data['redirect_uri'], $data['scope']);
 }
 public function retrieveAccessToken($accessToken)
 {
     $data = Json::decode(Base64Url::decode($accessToken));
     return new AccessToken($data['client_id'], $data['user_id'], $data['issued_at'], $data['scope']);
 }