code: void open(TopologyContext context, SpoutOutputCollector collector,
                int checkpointInterval, KeyValueState<String, CheckPointState> checkpointState) {
          this.context = context;
          this.collector = collector;
          this.checkpointInterval = checkpointInterval;
          this.sleepInterval = checkpointInterval / 10;
          this.checkpointState = checkpointState;
          this.curTxState = checkpointState.get(TX_STATE_KEY);
          lastCheckpointTs = 0;
          recoveryStepInProgress = false;
          checkpointStepInProgress = false;
          recovering = true;
      }
docs: package access for unit test