public URL getUrl() {
		return url;
	}
A class that knows how to provide an icon and the URL for that icon.  If {@link #getUrl()}
returns a non-null value, then that is the URL used to originally load the icon in this class.

<p>If {@link #getUrl()} returns null, then {@link #getOrCreateUrl()} can be used to create a
value URL by writing out the image for this class's icon.
Ghidra/Framework/Gui/src/main/java/resources/IconProvider.java