docs: public static PeriodFormatter alternate() {
          if (cAlternate == null) {
              cAlternate = new PeriodFormatterBuilder()
                  .appendLiteral("P")
                  .printZeroAlways()
                  .minimumPrintedDigits(4)
                  .appendYears()
                  .minimumPrintedDigits(2)
                  .appendMonths()
                  .appendDays()
                  .appendSeparatorIfFieldsAfter("T")
                  .appendHours()
                  .appendMinutes()
                  .appendSecondsWithOptionalMillis()
                  .toFormatter();
          }
          return cAlternate;
      }