Port info is always zero after a service is published

[DeepakArora76]

Just wondering why the port information is returned 0 when the publication of a service is successful?

Rx2Dnssd rxdnssd = new Rx2DnssdEmbedded(); 
BonjourService bs = new BonjourService.Builder(0, 0, Build.DEVICE, "_rxdnssd._tcp", null).port(123).build();
registerDisposable = rxDnssd.register(bs)
        .subscribeOn(Schedulers.io())
        .observeOn(AndroidSchedulers.mainThread())
        .subscribe(bonjourService -> {
            Log.i("TAG", "Register successfully " + bonjourService.toString());
        }, throwable -> {
            Log.e("TAG", "error", throwable);
        });