public static function setDefaultACL($acl, $withAccessForCurrentUser)
    {
        self::$defaultACLWithCurrentUser = null;
        self::$lastCurrentUser = null;
        if ($acl)
        {
            self::$defaultACL = clone $acl;
            self::$defaultACL->_setShared(true);
            self::$defaultACLUsesCurrentUser = $withAccessForCurrentUser;
        } else
        {
            self::$defaultACL = null;
        }
    }