### Question:
JsonConverter { public static String toJson(Object o) { return GSON.toJson(o); }  static String toJson(Object o); static T fromJson(String json, Class<T> clazz); static T fromJson(Reader reader, Class<T> clazz);  }### Answer:
@Test public void test() { GenericEntity entity = new GenericEntity(); GenericEntity element = new GenericEntity(); element.put("tire", "Yokohama"); entity.put("car", element); assertEquals("{\"car\":{\"tire\":\"Yokohama\"}}", JsonConverter.toJson(entity)); }