@Override
  public void shipped() throws IOException {
    super.shipped();
    this.freeAllReferencedMobCells();
  }
Firstly reads the cells from the HBase. If the cell is a reference cell (which has the
reference tag), the scanner need seek this cell from the mob file, and use the cell found from
the mob file as the result.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/ReversedMobStoreScanner.java