docs: public SingleOutputStreamOperator<T> assignTimestampsAndWatermarks(
  			AssignerWithPunctuatedWatermarks<T> timestampAndWatermarkAssigner) {
  
  		// match parallelism to input, otherwise dop=1 sources could lead to some strange
  		// behaviour: the watermark will creep along very slowly because the elements
  		// from the source go to each extraction operator round robin.
  		final int inputParallelism = getTransformation().getParallelism();
  		final AssignerWithPunctuatedWatermarks<T> cleanedAssigner = clean(timestampAndWatermarkAssigner);
  
  		TimestampsAndPunctuatedWatermarksOperator<T> operator =
  				new TimestampsAndPunctuatedWatermarksOperator<>(cleanedAssigner);
  
  		return transform("Timestamps/Watermarks", getTransformation().getOutputType(), operator)
  				.setParallelism(inputParallelism);
  	}