docs: private static long convertByWeekyear(final long instant, Chronology from, Chronology to) {
          long newInstant;
          newInstant = to.weekyear().set(0, from.weekyear().get(instant));
          newInstant = to.weekOfWeekyear().set(newInstant, from.weekOfWeekyear().get(instant));
          newInstant = to.dayOfWeek().set(newInstant, from.dayOfWeek().get(instant));
          newInstant = to.millisOfDay().set(newInstant, from.millisOfDay().get(instant));
          return newInstant;
      }