*
* @param int $httpCode HTTP status code to send to the client
* @param string|Message $content Content of the message
- * @param string|Message $header Content of the header (\<title\> and \<h1\>)
+ * @param string|Message|null $header Content of the header (\<title\> and \<h1\>)
*/
public function __construct( $httpCode, $content, $header = null ) {
parent::__construct( $content );