sp = new SPRedirectFormAuthenticator();
sp.setContainer(context);
sp.testStart();
session.clear();
request.clear();
request.setSession(session);
request.setUserPrincipal(genericPrincipal);
request.setParameter("SAMLResponse", RedirectBindingUtil.urlDecode(logoutResponse));
request.setParameter("RelayState", relayState);
request.setContext(context);