WicketTester can't test HttpSession transfer

After login into the Wicket Session it is recommended to call changeSessionId() to prevent session fixation. Unfortunately I can't use the WicketTester with the MockHttpServletRequest to test this behavior. After login all my session attributes are gone due to call of Session#invalidate() which removes all attributes.
See MockHttpServletRequest#changeSessionId() and MockHttpSession#invalidate().
Actually changing the Session Id is part of the HttpServletContainer implementation but is there a way to simulate this within the Wicket framework?