MulticastSocketFactoryImpl determines whether it can use the "MulticastSocket(SocketAddress bindaddr)" constructor variant based on this:

this.linuxlike = (value != null) && (value.toLowerCase().startsWith("linux") || value.toLowerCase().startsWith("mac") || value.toLowerCase().startsWith("hp"));

JGroups when doing a similiar test also allows Solaris via including (value.toLowerCase().startsWith("sun") in the test.

(Tangent: JGroups doesn't allow "mac", which sounds like a good topic for discussion between the respective teams.)