code: public RawKeyValueIterator sort() {
      MergeSort m = new MergeSort(this);
      int count = super.count;
      if (count == 0) return null;
      int [] pointers = super.pointers;
      int [] pointersCopy = new int[count];
      System.arraycopy(pointers, 0, pointersCopy, 0, count);
      m.mergeSort(pointers, pointersCopy, 0, count);
      return new MRSortResultIterator(super.keyValBuffer, pointersCopy, 
                                      super.startOffsets, super.keyLengths, super.valueLengths);
    }
docs: The sort method derived from BasicTypeSorterBase and overridden here