code: private void cleanRestoredHandles() throws Exception {
  		synchronized (pendingCheckpoints) {
  
  			Iterator<PendingCheckpoint> pendingCheckpointIt = pendingCheckpoints.iterator();
  			while (pendingCheckpointIt.hasNext()) {
  				PendingCheckpoint pendingCheckpoint = pendingCheckpointIt.next();
  
  				if (committer.isCheckpointCommitted(pendingCheckpoint.subtaskId, pendingCheckpoint.checkpointId)) {
  					pendingCheckpoint.stateHandle.discardState();
  					pendingCheckpointIt.remove();
  				}
  			}
  		}
  	}
docs: Called at {@link #open()} to clean-up the pending handle list.
  It iterates over all restored pending handles, checks which ones are already
  committed to the outside storage system and removes them from the list.