public String getWindowSubMenuName() {
		return windowMenuGroup;
	}
Returns the name of a cascading sub-menu name to use when showing this provider in the
"Window" menu. If the group name is null, the item will appear in the top-level menu.
@return the menu group for this provider or null if this provider should appear in the
top-level menu.
Ghidra/Framework/Docking/src/main/java/docking/ComponentProvider.java