void refresh(String typeString) {
			removeAllElements();
			if (typeString != null) {
				BookmarkManager manager = program.getBookmarkManager();
				String[] categories = manager.getCategories(typeString);
				for (String element : categories) {
					addElement(element);
				}
			}
		}
Class for the combo box model to hold list of categories.
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/bookmark/BookmarkProvider.java