how to identify http requests made with a java app

I am an avid Go player and play on the Kiseido Go Server.

The only client I know is the one app CGoban which operates in desktop Java (http://ift.tt/1CeNkdv), or if you wish as a Java applet.

Maybe I would like to write an open source client, but the KGS protocol is a well-kept secret. Is there any way to catch the requests made by the *.jar file to the Go server?