problem invalidating servlet

[Matt Bauer]

I have this small bit of code that handles a log out.  What I want to do
is invalidate the session and put a new on in its place.  The problem is
when I try to set the attribute, I get an exception telling my the
session is invalidated.  Am I missing something?

if (event instanceof LogoutEvent) {
     request.getSession().invalidate();
     HttpSession validSession = request.getSession();
     validSession.setAttribute(WebKeys.ModelManagerKey, mm);
}

Thanks

M