code: @PublicEvolving
  	public <W extends Window> AllWindowedStream<T, W> windowAll(WindowAssigner<? super T, W> assigner) {
  		return new AllWindowedStream<>(this, assigner);
  	}
docs: Windows this data stream to a {@code AllWindowedStream}, which evaluates windows
  over a non key grouped stream. Elements are put into windows by a
  {@link org.apache.flink.streaming.api.windowing.assigners.WindowAssigner}. The grouping of
  elements is done by window.
  
  <p>A {@link org.apache.flink.streaming.api.windowing.triggers.Trigger} can be defined to specify
  when windows are evaluated. However, {@code WindowAssigners} have a default {@code Trigger}
  that is used if a {@code Trigger} is not specified.
  
  <p>Note: This operation is inherently non-parallel since all elements have to pass through
  the same operator instance.
  
  @param assigner The {@code WindowAssigner} that assigns elements to windows.
  @return The trigger windows data stream.