docs: public static PeriodType seconds() {
          PeriodType type = cSeconds;
          if (type == null) {
              type = new PeriodType(
                  "Seconds",
                  new DurationFieldType[] { DurationFieldType.seconds() },
                  new int[] { -1, -1, -1, -1, -1, -1, 0, -1, }
              );
              cSeconds = type;
          }
          return type;
      }