### Question:
JsonUtil { public static <T> String stringify(T value) throws JsonProcessingException { return mapper.writeValueAsString(value); }  static String stringify(T value); static T fromJsonObject(String jsonString, Class<T> clazz); static List<T> fromJsonArray(String jsonString, 
			Class<T> elementClass); static JsonNode readTree(String jsonString); static T treeToValue(JsonNode node, Class<T> clazz); static Set<ValidationMessage> validate(JsonNode node, String schema);  }### Answer:
@Test public void stringify() throws JsonProcessingException { TestBean bean = new TestBean(); bean.setText("a"); bean.setIntNumber(1); bean.setDoubleNumber(2.1); bean.setDate(LocalDateTime.of(2020, 5, 14, 20, 55)); String jsonString = JsonUtil.stringify(bean); assertThat(jsonString) .contains("\"text\":\"a\"") .contains("\"intNumber\":1") .contains("\"doubleNumber\":2.1") .contains("\"date\":\"2020-05-14T20:55:00\""); }