8332535: Mark java/nio/channels/DatagramChannel/Loopback.java as inte…

…rmittent

Signed-off-by: sendaoYan <yansendao.ysd@alibaba-inc.com>

test/jdk/java/nio/channels/DatagramChannel/Loopback.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -23,6 +23,7 @@
 
 /* @test
  * @bug 8236184
+ * @key intermittent
  * @library /test/lib
  * @build jdk.test.lib.NetworkConfiguration
  *        jdk.test.lib.net.IPSupport
@@ -160,7 +161,7 @@ static void test(ProtocolFamily family, InetAddress group, NetworkInterface ni)
                         if (sender != null) {
                             System.out.format("received %s from %s%n", dst, sender);
                             senderPort = ((InetSocketAddress) sender).getPort();
-                            assertTrue(senderPort != localPort, "Unexpected message");
+                            assertTrue(senderPort != localPort, "Unexpected message: localPort=" + localPort);
                         }
                     }
                 }