docs: public static ZonedChronology getInstance(Chronology base, DateTimeZone zone) {
          if (base == null) {
              throw new IllegalArgumentException("Must supply a chronology");
          }
          base = base.withUTC();
          if (base == null) {
              throw new IllegalArgumentException("UTC chronology must not be null");
          }
          if (zone == null) {
              throw new IllegalArgumentException("DateTimeZone must not be null");
          }
          return new ZonedChronology(base, zone);
      }