Some platforms do not support multicasting, but the current spec requires that it is supported. It seems reasonable to relax this, somewhat, so that multicasting is effectively optional on these platforms.
java.net.MulticastSocket.joinGroup and java.nio.channels.MulticastChannel.join method specifications should be updated to indicate that an exception will be thrown if invoked on a platform that does not support multicasting. http://cr.openjdk.java.net/~chegar/8157166/ https://bugs.openjdk.java.net/browse/JDK-8157166 -Chris.
