Added a better comment as to why we have to check

the channels even though the negative channels would
pass through as the default channels just fine.
The key is avoiding UDP calls... they will get
translated into a regular send.

jme3-networking/src/main/java/com/jme3/network/service/rpc/RpcConnection.java

@@ -116,6 +116,11 @@ public class RpcConnection {
         if( log.isLoggable(Level.FINEST) ) {
             log.log(Level.FINEST, "Sending:{0}  on channel:{1}", new Object[]{msg, channel});
         }
+        
+        // Prevent non-async messages from being send as UDP
+        // because there is a high probabilty that this would block
+        // forever waiting for a response.  For async calls it's ok
+        // so it doesn't do the check.
         if( channel >= 0 ) {        
             connection.send(channel, msg);
         } else {