code: public OverlayIcon withOverlay(ImageIcon ... overlays) {
  		if(overlays != null) {
  			for(ImageIcon overlay : overlays) {
  				this.overlays.add(overlay);
  			}
  		}
  		return this;
  	}
docs: Adds an overlay icon to the base icon.
  
  @param overlays
  the list of overlay icons to add.
  @return
  the object itself, for method chaining.