You can achieve your goal by using below code
private void doPortForwarding() {
PortMapping[] desiredMapping = new PortMapping[2];
desiredMapping[0] = new PortMapping(8123, InetAddress.getLocalHost().getHostAddress(),
PortMapping.Protocol.TCP, " TCP POT Forwarding");
desiredMapping[1] = new PortMapping(8123, InetAddress.getLocalHost().getHostAddress(),
PortMapping.Protocol.UDP, " UDP POT Forwarding");
UpnpService upnpService = new UpnpServiceImpl();
RegistryListener registryListener = new PortMappingListener(desiredMapping);
upnpService.getRegistry().addListener(registryListener);
upnpService.getControlPoint().search();
}