code: public synchronized void updateAndAdd(JmxRequest pJmxReq, JSONObject pJson) {
          long timestamp = System.currentTimeMillis() / 1000;
          pJson.put(KEY_TIMESTAMP,timestamp);
  
          RequestType type  = pJmxReq.getType();
          HistoryUpdater updater = historyUpdaters.get(type);
          if (updater != null) {
              updater.updateHistory(pJson,pJmxReq,timestamp);
          }
      }
docs: Update the history store with the value of an an read, write or execute operation. Also, the timestamp
  of the insertion is recorded. Also, the recorded history values are added to the given json value.
  
  @param pJmxReq request for which an entry should be added in this history store
  @param pJson the JSONObject to which to add the history.