public void attributeRemoved(HttpSessionBindingEvent se) {
// user tracker
UserTracker userTracker = getWebApplicationContext(se).getBean(UserTracker.class);
if(AttributeKeys.USER_ID_KEY.equals(se.getName())) {
userTracker.untrack(se.getName(), se.getValue());
}
}
public void attributeReplaced(HttpSessionBindingEvent se) {
}