JSONObject toJSONString错误的解决

Model model = new Model();
String json = JSONObject.toJSONString(model); // serializes model to Json
Model model2 = JSONObject.parseObject(json, Model.class); // deserializes json into model2

SingleCallByTtsRequest extends RpcAcsRequest<SingleCallByTtsResponse> 
RpcAcsRequest<T extends AcsResponse> extends AcsRequest<T> 
SingleCallByTtsResponse extends AcsResponse

public static String toJSONString(Object object)

public static String toJSONString(Object object, SerializerFeature… features)

JSONUtils.toJSONString(null); //返回一个为"null"的字符串

public class JSONUtils {
    public static String toJSONString(Object o) {
        JSONWriter writer = new JSONWriter();
        writer.writeObject(o);
        return writer.toString();
    }
    
    public static Object parse(String text) {
        JSONParser parser = new JSONParser(text);
        return parser.parse();
    }
}
    public void writeNull() {
        write("null");
    }
    
    @SuppressWarnings({ "unchecked", "rawtypes" })
    public void writeObject(Object o) {
        if (o == null) {
            writeNull();
            return;
        }