protected function makeOAuth2Request($path, $method = 'GET', $params = array()) {
    if ((!isset($params['access_token']) || empty($params['access_token'])) && $oauth_token = $this->getAccessToken()) {
      $params['access_token'] = $oauth_token;
    }
    
    return $this->makeRequest($path, $method, $params);
  }