public function parseHeaders(EnvironmentInterface $environment)
    {
        foreach ($environment as $key => $value) {
            $key = strtoupper($key);

            if (strpos($key, 'HTTP_') === 0 || in_array($key, $this->special)) {
                if ($key === 'HTTP_CONTENT_TYPE' || $key === 'HTTP_CONTENT_LENGTH') {
                    continue;
                }

                parent::set($this->normalizeKey($key), array($value));
            }
        }
    }