### Question:
JSONUtils { public static ObjectNode createObjectNode() { return objectMapper.createObjectNode(); } private  JSONUtils(); static ArrayNode createArrayNode(); static ObjectNode createObjectNode(); static JsonNode toJsonNode(Object obj); static String toJsonString(Object object, SerializationFeature feature); static T parseObject(String json, Class<T> clazz); static List<T> toList(String json, Class<T> clazz); static boolean checkJsonValid(String json); static String findValue(JsonNode jsonNode, String fieldName); static Map<String, String> toMap(String json); static Map<K, V> toMap(String json, Class<K> classK, Class<V> classV); static String toJsonString(Object object); static ObjectNode parseObject(String text); static ArrayNode parseArray(String text);  }### Answer:
@Test public void createObjectNodeTest() { String jsonStr = "{\"a\":\"b\",\"b\":\"d\"}"; ObjectNode objectNode = JSONUtils.createObjectNode(); objectNode.put("a","b"); objectNode.put("b","d"); String s = JSONUtils.toJsonString(objectNode); Assert.assertEquals(s, jsonStr); }