Create a service discovery request to search specified UPnP services.
if (st == null) {
throw new IllegalArgumentException("search target cannot be null");
}
StringBuffer sb = new StringBuffer();
sb.append(String.format(Locale.US, "%02x", WifiP2pUpnpServiceInfo.VERSION_1_0));
sb.append(WifiP2pServiceInfo.bin2HexStr(st.getBytes()));
return new WifiP2pUpnpServiceRequest(sb.toString());