static TimerResult fromJson(String json) {
    return JsonUtil.parse(json, TimerResultParser::fromJson);
  }
@Test
  public void extraFields() {
    assertThat(
            TimerResultParser.fromJson(
                "{\"count\":44,\"time-unit\":\"hours\",\"total-duration\":24,\"extra\": \"value\"}"))
        .isEqualTo(TimerResult.of(TimeUnit.HOURS, Duration.ofHours(24), 44));
  }