docs: CompletedCheckpointStats.DiscardCallback reportCompletedCheckpoint(String externalPointer) {
  		CompletedCheckpointStats completed = new CompletedCheckpointStats(
  			checkpointId,
  			triggerTimestamp,
  			props,
  			numberOfSubtasks,
  			new HashMap<>(taskStats),
  			currentNumAcknowledgedSubtasks,
  			currentStateSize,
  			currentAlignmentBuffered,
  			latestAcknowledgedSubtask,
  				externalPointer);
  
  		trackerCallback.reportCompletedCheckpoint(completed);
  
  		return completed.getDiscardCallback();
  	}