docs: private <T> Collection<Integer> transformSource(SourceTransformation<T> source) {
  		String slotSharingGroup = determineSlotSharingGroup(source.getSlotSharingGroup(), Collections.emptyList());
  
  		streamGraph.addSource(source.getId(),
  				slotSharingGroup,
  				source.getCoLocationGroupKey(),
  				source.getOperator(),
  				null,
  				source.getOutputType(),
  				"Source: " + source.getName());
  		if (source.getOperator().getUserFunction() instanceof InputFormatSourceFunction) {
  			InputFormatSourceFunction<T> fs = (InputFormatSourceFunction<T>) source.getOperator().getUserFunction();
  			streamGraph.setInputFormat(source.getId(), fs.getFormat());
  		}
  		streamGraph.setParallelism(source.getId(), source.getParallelism());
  		streamGraph.setMaxParallelism(source.getId(), source.getMaxParallelism());
  		return Collections.singleton(source.getId());
  	}