src/vs/platform/actions/browser/menuEntryActionViewItem.ts/SubmenuEntryActionViewItem/constructor
class SubmenuEntryActionViewItem:	constructor(
		action: SubmenuItemAction,
		options: IDropdownMenuActionViewItemOptions | undefined,
		@IContextMenuService contextMenuService: IContextMenuService,
		@IThemeService protected _themeService: IThemeService
	) {
		const dropdownOptions = Object.assign({}, options ?? Object.create(null), {
			menuAsChild: options?.menuAsChild ?? false,
			classNames: options?.classNames ?? (ThemeIcon.isThemeIcon(action.item.icon) ? ThemeIcon.asClassName(action.item.icon) : undefined),
		});

		super(action, { getActions: () => action.actions }, contextMenuService, dropdownOptions);
	}