@edu.umd.cs.findbugs.annotations.SuppressWarnings(value = "IS2_INCONSISTENT_SYNC",
      justification = "The only possible race method is startCancel")
  @Override
  public void setCellScanner(final ExtendedCellScanner cellScanner) {
    this.cellScanner = cellScanner;
  }
Returns One-shot cell scanner (you cannot back it up and restart)
hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/HBaseRpcControllerImpl.java