public static function loadTzMaps()
    {
        if (!is_null(self::$map)) {
            return;
        }

        self::$map = array_merge(
            include __DIR__.'/timezonedata/windowszones.php',
            include __DIR__.'/timezonedata/lotuszones.php',
            include __DIR__.'/timezonedata/exchangezones.php',
            include __DIR__.'/timezonedata/php-workaround.php'
        );
    }