code: public boolean supersedes(RangeTombstone rt, Comparator<Composite> comparator)
      {
          if (rt.data.markedForDeleteAt > data.markedForDeleteAt)
              return false;
  
          return comparator.compare(min, rt.min) <= 0 && comparator.compare(max, rt.max) >= 0;
      }
docs: This tombstone supersedes another one if it is more recent and cover a
  bigger range than rt.