src/vs/platform/actions/common/actions.ts/SubmenuItemAction/constructor
class SubmenuItemAction:	constructor(
		readonly item: ISubmenuItem,
		readonly hideActions: IMenuItemHide | undefined,
		actions: IAction[],
	) {
		super(`submenuitem.${item.submenu.id}`, typeof item.title === 'string' ? item.title : item.title.value, actions, 'submenu');
	}