public void shipped(RawCellBuilder cellBuilder) {
    if (largestRowRef != null) {
      largestRow = CellUtil.cloneRow(largestRowRef);
      largestRowRef = null;
    }
    if (largestCellRef != null) {
      largestCell = RowStatisticsUtil.cloneWithoutValue(cellBuilder, largestCellRef);
      largestCellRef = null;
    }
  }
Clone the cell refs so they can be cleaned up by {@link Shipper#shipped()}. Doing this lazily
here, rather than eagerly in the above two methods can save us on some allocations. We might
change the largestCell/largestRow multiple times between shipped() calls.
hbase-examples/src/main/java/org/apache/hadoop/hbase/coprocessor/example/row/stats/RowStatisticsImpl.java