Added a new extension point to contribute fragment to UDP-based auto discovery.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@17797 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/UDPBroadcastThread.java

@@ -69,6 +69,10 @@ public class UDPBroadcastThread extends Thread {
                     tag(buf,"version",Hudson.VERSION);
                     tag(buf,"url",hudson.getRootUrl());
                     tag(buf,"slave-port",tal==null?null:tal.getPort());
+
+                    for (UDPBroadcastFragment f : UDPBroadcastFragment.all())
+                        f.buildFragment(buf,sender);
+
                     buf.append("</hudson>");
 
                     b.clear();