code: public int getPreviousRangeIndex() {
          int length = rangeIndexList.size();
          if (length == 2) {
              rangeIndexList.remove(1);
              return 0;
          } else if (length == 1) {
              return 0;
          }
          rangeIndexList.remove(length - 1);
          rangeIndexList.remove(length - 2);
          Integer rindex = rangeIndexList.get(length - 3);
          return rindex.intValue();
      }
docs: ************************************************************************
  getPreviousRangeIndex The range index for walkHash().
  ***********************************************************************