code: private static Chronology of0(String id) {
          Chronology chrono = CHRONOS_BY_ID.get(id);
          if (chrono == null) {
              chrono = CHRONOS_BY_TYPE.get(id);
          }
          return chrono;
      }
docs: Obtains an instance of {@code Chronology} from a chronology ID or
  calendar system type.
  
  @param id  the chronology ID or calendar system type, not null
  @return the chronology with the identifier requested, or {@code null} if not found