Jetty or Tomcat ?
My guess is that your JSP is creating the session for you - I think that there is a flag that you can set to say whether you will require a session or not.
I'm a Jetty man - so if this is not it you will need to find some Tomcat people.
If it is the JSP thing, please report back to the forum so I can put it in my FAQ.
The solution is to put that in the jsp file :
<%@ page session="false">