public void setResponse(Message response, final ExtendedCellScanner cells) {
    synchronized (this) {
      if (done) {
        return;
      }
      this.done = true;
      this.response = response;
      this.cells = cells;
    }
    callComplete();
  }
Set the return value when there is no error. Notify the caller the call is done.
@param response return value of the call.
@param cells    Can be null
hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/Call.java