docs: public static BuddhistChronology getInstance(DateTimeZone zone) {
          if (zone == null) {
              zone = DateTimeZone.getDefault();
          }
          BuddhistChronology chrono = cCache.get(zone);
          if (chrono == null) {
              // First create without a lower limit.
              chrono = new BuddhistChronology(GJChronology.getInstance(zone, null), null);
              // Impose lower limit and make another BuddhistChronology.
              DateTime lowerLimit = new DateTime(1, 1, 1, 0, 0, 0, 0, chrono);
              chrono = new BuddhistChronology(LimitChronology.getInstance(chrono, lowerLimit, null), "");
              BuddhistChronology oldChrono = cCache.putIfAbsent(zone, chrono);
              if (oldChrono != null) {
                  chrono = oldChrono;
              }
          }
          return chrono;
      }