getUsers().clear();
    public void pageBeginRender(PageEvent event) {        // Initialize the user and users properties if necessary        if (getUser() == null) {                    setUser(new User());        }        if (getUsers() == null) {            setUsers(new ArrayList());        }                        // On navigating to this page and rendering for the first time, we don't        // want to perform a search, because the user hasn't entered any search        // criteria yet.        if (isFirstRender()) {            setFirstRender(false);        } else {            search(event.getRequestCycle());        }    }