Add unit test to the modules: 
dubbo-registry/dubbo-registry-multicast
   dubbo-registry/dubbo-registry-redis
  dubbo-registry/dubbo-registry-zookeeper 
if (urls != null && !urls.isEmpty()) {
                for (URL u : urls) {
                    if (UrlUtils.isMatch(url, u)) {
                        String host = remoteAddress != null && remoteAddress.getAddress() != null
                                ? remoteAddress.getAddress().getHostAddress() : url.getIp();
                        if (url.getParameter("unicast", true) 
                                && !NetUtils.getLocalHost().equals(host)) { 
                            unicast(Constants.REGISTER + " " + u.toFullString(), host);
                        } else {
                            broadcast(Constants.REGISTER + " " + u.toFullString());
                        }
                    }
                }
            }
        }/* else if (msg.startsWith(UNSUBSCRIBE)) {
        }*/
    }
    private void broadcast(String msg) {
        if (logger.isInfoEnabled()) {
            logger.info("Send broadcast message: " + msg + " to " + mutilcastAddress + ":" + mutilcastPort);
        }
        try {
            byte[] data = (msg + "\n").getBytes();
            DatagramPacket hi = new DatagramPacket(data, data.length, mutilcastAddress, mutilcastPort);
            mutilcastSocket.send(hi);
        } catch (Exception e) {
            throw new IllegalStateException(e.getMessage(), e);
        }
    }
    private void unicast(String msg, String host) {