code: @NotNull
    public static ObjectMapper createMapper() {
      final ObjectMapper mapper = new ObjectMapper();
      mapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
      mapper.enable(SerializationFeature.INDENT_OUTPUT);
      mapper.setDateFormat(new ISO8601DateFormat());
      mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
      return mapper;
    }
docs: Creating mapper for serialize/deserialize data to JSON.