src/vs/platform/actions/common/actions.ts/SubmenuItemAction/constructor
class SubmenuItemAction:	constructor(
		readonly item: ISubmenuItem,
		private readonly _menuService: IMenuService,
		private readonly _contextKeyService: IContextKeyService,
		private readonly _options?: IMenuActionOptions
	) {
		super(`submenuitem.${item.submenu.id}`, typeof item.title === 'string' ? item.title : item.title.value, [], 'submenu');
	}