docs: public static PeriodType yearWeekDay() {
          PeriodType type = cYWD;
          if (type == null) {
              type = new PeriodType(
                  "YearWeekDay",
                  new DurationFieldType[] {
                      DurationFieldType.years(),
                      DurationFieldType.weeks(), DurationFieldType.days(),
                  },
                  new int[] { 0, -1, 1, 2, -1, -1, -1, -1, }
              );
              cYWD = type;
          }
          return type;
      }