code: static JapaneseEra from(LocalDate date) {
          if (date.isBefore(MEIJI.since)) {
              throw new DateTimeException("Date too early: " + date);
          }
          JapaneseEra[] known = KNOWN_ERAS.get();
          for (int i = known.length - 1; i >= 0; i--) {
              JapaneseEra era = known[i];
              if (date.compareTo(era.since) >= 0) {
                  return era;
              }
          }
          return null;
      }
docs: Obtains an instance of {@code JapaneseEra} from a date.
  
  @param date  the date, not null
  @return the Era singleton, never null