protected function getHeaders()
    {
        if (function_exists('getallheaders')) {
            return getallheaders();
        }
        $arr_headers = [];
        foreach ($_SERVER as $str_key => $str_value) {
            if (strpos($str_key, 'HTTP_') === 0) {
                $arr_headers[str_replace(' ', '-', ucwords(strtolower(str_replace('_', ' ', substr($str_key, 5)))))] = $str_value;
            }
        }
        return $arr_headers;
    }