public static function createForward4($sourceAddress, $sourcePort, $targetAddress, $targetPort, $version = 2) {
        $result = new static();
        $result->version = $version;
        $result->sourceAddress = $sourceAddress;
        $result->targetPort = $targetPort;
        $result->targetAddress = $targetAddress;
        $result->sourcePort = $sourcePort;
        return $result;
    }