protected function getAllHeaders()
    {
        $headers = [];

        foreach ($_SERVER as $key => $value) {
            if (substr($key, 0, 5) == 'HTTP_') {
                $key = substr($key, 5);
                $key = str_replace('_', ' ', strtolower($key));
                $key = str_replace(' ', '-', ucwords($key));

                $headers[$key] = $value;
            }
        }

        return $headers;
    }