@Override
  public CreateFunctionMessage getCreateFunctionMessage(String messageBody) {
    try {
      return mapper.readValue(messageBody, JSONCreateFunctionMessage.class);
    }
    catch (Exception exception) {
      throw new IllegalArgumentException("Could not construct JSONCreateFunctionMessage.", exception);
    }
  }
MessageDeserializer implementation, for deserializing from JSON strings.
hcatalog/server-extensions/src/main/java/org/apache/hive/hcatalog/messaging/json/JSONMessageDeserializer.java