code: @PublicEvolving
  	public WindowedStream<T, K, W> allowedLateness(Time lateness) {
  		final long millis = lateness.toMilliseconds();
  		checkArgument(millis >= 0, "The allowed lateness cannot be negative.");
  
  		this.allowedLateness = millis;
  		return this;
  	}
docs: Sets the time by which elements are allowed to be late. Elements that
  arrive behind the watermark by more than the specified time will be dropped.
  By default, the allowed lateness is {@code 0L}.
  
  <p>Setting an allowed lateness is only valid for event-time windows.