@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 top of the menu so that universal popup
actions are always at the bottom (e.g., Copy for tables).
Ghidra/Framework/Docking/src/main/java/docking/menu/MenuManager.java