code: public static SlidingEventTimeWindows of(Time size, Time slide) {
  		return new SlidingEventTimeWindows(size.toMilliseconds(), slide.toMilliseconds(), 0);
  	}
docs: Creates a new {@code SlidingEventTimeWindows} {@link WindowAssigner} that assigns
  elements to sliding time windows based on the element timestamp.
  
  @param size The size of the generated windows.
  @param slide The slide interval of the generated windows.
  @return The time policy.