What is the purpose of the change

fix #6733, multicast use valid network interface

Brief changelog

MulticastSocket should use a valid network interface, use getValidNetworkInterfaces instead of NetworkInterface.getNetworkInterfaces.

Just modified dubbo-common/src/main/java/org/apache/dubbo/common/utils/NetUtils.java

@@ -471,10 +471,8 @@ public class NetUtils {
 
     public static void setInterface(MulticastSocket multicastSocket, boolean preferIpv6) throws IOException {
         boolean interfaceSet = false;
-        Enumeration interfaces = NetworkInterface.getNetworkInterfaces();
-        while (interfaces.hasMoreElements()) {
-            NetworkInterface i = (NetworkInterface) interfaces.nextElement();
-            Enumeration addresses = i.getInetAddresses();
+        for (NetworkInterface networkInterface : getValidNetworkInterfaces()) {
+            Enumeration addresses = networkInterface.getInetAddresses();
             while (addresses.hasMoreElements()) {
                 InetAddress address = (InetAddress) addresses.nextElement();
                 if (preferIpv6 && address instanceof Inet6Address) {

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