docs: @SuppressWarnings({ "unchecked", "rawtypes" })
  	public DataStream<T> closeWith(DataStream<T> feedbackStream) {
  
  		Collection<StreamTransformation<?>> predecessors = feedbackStream.getTransformation().getTransitivePredecessors();
  
  		if (!predecessors.contains(this.transformation)) {
  			throw new UnsupportedOperationException(
  					"Cannot close an iteration with a feedback DataStream that does not originate from said iteration.");
  		}
  
  		((FeedbackTransformation) getTransformation()).addFeedbackEdge(feedbackStream.getTransformation());
  
  		return feedbackStream;
  	}