Create a gson object that formats the time zone. JSON parsing time formatting zoneddatetime

I was sent by different modules once ZonedDateTime Time format is different , According to the types of different modules new A custom gson Object to parse json.

    private Gson getMyGson() {
    
        return new GsonBuilder().registerTypeAdapter(ZonedDateTime.class, new JsonDeserializer<ZonedDateTime>() {
    
            @Override
            public ZonedDateTime deserialize(JsonElement json, Type type, JsonDeserializationContext jsonDeserializationContext) throws JsonParseException {
    
                if (json == null) {
    
                    return null;
                }
                DateTimeFormatter fmt = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSS").withZone(ZoneId.systemDefault());
                return ZonedDateTime.from(fmt.parse(json.getAsString())).withZoneSameInstant(ZoneId.systemDefault());

            }
        }).registerTypeAdapter(ZonedDateTime.class, new JsonSerializer<ZonedDateTime>() {
    
            @Override
            public JsonElement serialize(ZonedDateTime zonedDateTime, Type type, JsonSerializationContext jsonSerializationContext) {
    
                DateTimeFormatter fmt = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSS");
                return new JsonPrimitive(fmt.format(zonedDateTime.truncatedTo(ChronoUnit.MILLIS)));
            }
        }).setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES).setDateFormat("yyyy-MM-dd HH:mm:ss.SSS").create();
    }