* @param string|null $expiry Timestamp of expiry in TS_MW format, or null if no expiry
*/
public function __construct( $userId = 0, $group = null, $expiry = null ) {
* @param string|null $expiry Timestamp of expiry in TS_MW format, or null if no expiry
*/
public function __construct( $userId = 0, $group = null, $expiry = null ) {