class LoginUtils {

    // get current login username
    public static String getUserInfo2JsonStr(HttpServletRequest request) {<FILL_FUNCTION_BODY>}
}

        Principal principal = request.getUserPrincipal();
        String username = principal.getName();
        Map<String, String> m = new HashMap<>();
        m.put("Username", username);

        return JSON.toJSONString(m);
    
<no_super_class>