public static void main(String[] args) throws JsonProcessingException {
        UnsignedLong unsignedLong = UnsignedLong.valueOf(123456789L);

        Map<String, Object> map = new HashMap<>();
        map.put("count", unsignedLong);

        //fastjson2
        System.out.println("fastjson2:  " + JSONObject.toJSONString(map));

        //jackson
        ObjectMapper objectMapper = new ObjectMapper();
        System.out.println("jackson:  " + objectMapper.writeValueAsString(map));

        //hutool-json
        System.out.println("hutool-json:  " + JSONUtil.toJsonStr(map));

        //gson
        Gson gson = new GsonBuilder().create();
        System.out.println("gson:  " + gson.toJson(map));
    }