public function setAccessControlExposeHeaders($headers)
    {
        // If hraders is array, parse to string.
        if (is_array($headers)) {
            $headers = implode(', ', $headers);
        }

        // The headers not is empty, append response hraders.
        if (!empty($headers)) {
            $this->setHeader('Access-Control-Expose-Headers', (string) $headers);
        }

        return $this;
    }