code: public static JapaneseEra valueOf(String japaneseEra) {
          Jdk8Methods.requireNonNull(japaneseEra, "japaneseEra");
          JapaneseEra[] known = KNOWN_ERAS.get();
          for (JapaneseEra era : known) {
              if (japaneseEra.equals(era.name)) {
                  return era;
              }
          }
          throw new IllegalArgumentException("Era not found: " + japaneseEra);
      }
docs: Returns the {@code JapaneseEra} with the name.
  <p>
  The string must match exactly the name of the era.
  (Extraneous whitespace characters are not permitted.)
  
  @param japaneseEra  the japaneseEra name; non-null
  @return the {@code JapaneseEra} singleton, never null
  @throws IllegalArgumentException if there is not JapaneseEra with the specified name