private void updateSequenceId(final Iterable<List<ExtendedCell>> cellItr, final long sequenceId)
    throws IOException {
    for (List<ExtendedCell> cells : cellItr) {
      if (cells == null) {
        return;
      }
      for (ExtendedCell cell : cells) {
        cell.setSequenceId(sequenceId);
      }
    }
  }
Complete taking the snapshot on the region. Writes the region info and adds references to the
working snapshot directory. TODO for api consistency, consider adding another version with no
{@link ForeignExceptionSnare} arg. (In the future other cancellable HRegion methods could
eventually add a {@link ForeignExceptionSnare}, or we could do something fancier).
@param desc     snapshot description object
@param exnSnare ForeignExceptionSnare that captures external exceptions in case we need to bail
                out. This is allowed to be null and will just be ignored in that case.
@throws IOException if there is an external or internal error causing the snapshot to fail
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java