public function storeAuthorizationCode(AuthorizationCode $authorizationCode)
 {
     return Base64Url::encode(Json::encode(array('client_id' => $authorizationCode->getClientId(), 'user_id' => $authorizationCode->getUserId(), 'issued_at' => $authorizationCode->getIssuedAt(), 'redirect_uri' => $authorizationCode->getRedirectUri(), 'scope' => $authorizationCode->getScope())));
 }
 public function storeAccessToken(AccessToken $accessToken)
 {
     return Base64Url::encode(Json::encode(array('client_id' => $accessToken->getClientId(), 'user_id' => $accessToken->getUserId(), 'issued_at' => $accessToken->getIssuedAt(), 'scope' => $accessToken->getScope())));
 }