@Override
		public int compare(String group1, String group2) {
			if (group1 == null && group2 == null) {
				return 0;
			}
			if (group1 == null) {
				return 1;
			}
			if (group2 == null) {
				return -1;
			}
			return group1.compareTo(group2);
		}
This comparator puts null grouped items at the bottom of menus for menu bar menus so that
the ungrouped items will cluster at the end.
Ghidra/Framework/Docking/src/main/java/docking/menu/MenuManager.java