docs: private <T> Collection<Integer> transformPartition(PartitionTransformation<T> partition) {
  		StreamTransformation<T> input = partition.getInput();
  		List<Integer> resultIds = new ArrayList<>();
  
  		Collection<Integer> transformedIds = transform(input);
  		for (Integer transformedId: transformedIds) {
  			int virtualId = StreamTransformation.getNewNodeId();
  			streamGraph.addVirtualPartitionNode(transformedId, virtualId, partition.getPartitioner());
  			resultIds.add(virtualId);
  		}
  
  		return resultIds;
  	}