### Question:
JsonUtil { public static ObjectNode objectNodeFromMap(final Map<String, Object> map) { return (ObjectNode) getObjectMapper().valueToTree(map); }  static ObjectNode normalizeKeys(final ObjectNode objectNode); static Optional<String> getValueAsString(final ObjectNode node, final String key); static String getValueAsString(
      final ObjectNode node, final String key, final String defaultValue); static Optional<String> getString(final ObjectNode node, final String key); static String getString(
      final ObjectNode node, final String key, final String defaultValue); static OptionalInt getInt(final ObjectNode node, final String key); static int getInt(final ObjectNode node, final String key, final int defaultValue); static OptionalLong getLong(final ObjectNode json, final String key); static long getLong(final ObjectNode json, final String key, final long defaultValue); static Optional<Boolean> getBoolean(final ObjectNode node, final String key); static boolean getBoolean(
      final ObjectNode node, final String key, final boolean defaultValue); static ObjectNode createEmptyObjectNode(); static ObjectNode objectNodeFromMap(final Map<String, Object> map); static ObjectNode objectNodeFromString(final String jsonData); static ObjectNode objectNodeFromString(
      final String jsonData, final boolean allowComments); static String getJson(final Object objectNode); static String getJson(final Object objectNode, final boolean prettyPrint); static ObjectMapper getObjectMapper(); static Optional<ObjectNode> getObjectNode(final ObjectNode json, final String fieldKey); static Optional<ObjectNode> getObjectNode(
      final ObjectNode json, final String fieldKey, final boolean strict); static Optional<ArrayNode> getArrayNode(final ObjectNode json, final String fieldKey); static Optional<ArrayNode> getArrayNode(
      final ObjectNode json, final String fieldKey, final boolean strict);  }### Answer:
@Test public void objectNodeFromMap() { final Map<String, Object> map = new TreeMap<>(); map.put("a", 1); map.put("b", 2); final Map<String, Object> subMap = new TreeMap<>(); subMap.put("c", "bla"); subMap.put("d", 2L); map.put("subtree", subMap); final ObjectNode node = JsonUtil.objectNodeFromMap(map); assertThat(node.get("a").asInt()).isEqualTo(1); assertThat(node.get("b").asInt()).isEqualTo(2); assertThat(node.get("subtree").get("c").asText()).isEqualTo("bla"); assertThat(node.get("subtree").get("d").asLong()).isEqualTo(2L); }