code: public static String getStorageDir(DataSegment segment)
    {
      return JOINER.join(
          segment.getDataSource(),
          String.format(
              "%s_%s",
              segment.getInterval().getStart(),
              segment.getInterval().getEnd()
          ),
          segment.getVersion(),
          segment.getShardSpec().getPartitionNum()
      );
    }
docs: on segment deletion if segment being deleted was the only segment