checkNotNull(arg); // to fulfill null check
      }
    }
  }

  private enum Gender {
    MALE,
    FEMALE
  }

  private static class AllDefaultValuesChecker extends DefaultValueChecker {

    @SuppressWarnings("unused") // called by NullPointerTester
    @Keep
    public void checkDefaultValuesForTheseTypes(
        Gender gender,
        Integer integer,