code: private static String expandOffsetPattern(String offsetHM) {
          int idx_mm = offsetHM.indexOf("mm");
          if (idx_mm < 0) {
              throw new RuntimeException("Bad time zone hour pattern data");
          }
          String sep = ":";
          int idx_H = offsetHM.substring(0, idx_mm).lastIndexOf("H");
          if (idx_H >= 0) {
              sep = offsetHM.substring(idx_H + 1, idx_mm);
          }
          return offsetHM.substring(0, idx_mm + 2) + sep + "ss" + offsetHM.substring(idx_mm + 2);
      }
docs: TODO This code will be obsoleted once we add hour-minute-second pattern data in CLDR