@Override
    public void run() {
      for (RegionScanner scanner : scanners) {
        try {
          scanner.close();
        } catch (IOException e) {
          LOG.error("Exception while closing the scanner " + scanner, e);
        }
      }
    }
An RpcCallBack that creates a list of scanners that needs to perform callBack operation on
completion of multiGets.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RSRpcServices.java