protected function configureRefreshEndpoint(EndpointInterface $Endpoint)
    {
        $data = array();
        $data['client_id'] = $this->credentials['client_id'];
        $data['client_secret'] = $this->credentials['client_secret'];
        $data['grant_type'] = self::OAUTH_REFRESH_GRANT;
        $data['refresh_token'] = $this->token['refresh_token'];
        return $Endpoint->setData($data);
    }