@Override
		public URL getImageURL() {

			AttributeSet attributes = getElement().getAttributes();
			Object src = attributes.getAttribute(HTML.Attribute.SRC);
			if (src == null) {
				return null;
			}

			String srcString = src.toString().trim();
			IconProvider iconProvider = HelpBuildUtils.getRuntimeIcon(srcString);
			if (iconProvider != null && !iconProvider.isInvalid()) {
				// note: store the image off for later use; the url will not be used by us
				this.image = iconProvider.getImage();
				return iconProvider.getOrCreateUrl();
			}

			return doGetImageURL(srcString);
		}
Overridden to allow us to find images that are defined as constants in places like
{@link Icons}
Ghidra/Framework/Help/src/main/java/help/GHelpHTMLEditorKit.java