private function addRequestMethod(&$curlOptions) {
        $method = strtoupper($this->getOption(self::METHOD_KEY, 'GET'));
        switch ($method) {
            case 'GET':
                break;
            case 'POST':
                $curlOptions[CURLOPT_POST] = true;
                $curlOptions[CURLOPT_POSTFIELDS] = $this->getOption(self::DATA_KEY, array());
                break;
            default:
                $curlOptions[CURLOPT_CUSTOMREQUEST] = $method;
                $curlOptions[CURLOPT_POSTFIELDS] = $this->getOption(self::DATA_KEY, array());
        }
    }