src/vs/workbench/api/browser/mainThreadWorkspace.ts/MainThreadWorkspace/$updateWorkspaceFolders
class MainThreadWorkspace:	$updateWorkspaceFolders(extensionName: string, index: number, deleteCount: number, foldersToAdd: { uri: UriComponents, name?: string }[]): Promise<void> {
		const workspaceFoldersToAdd = foldersToAdd.map(f => ({ uri: URI.revive(f.uri), name: f.name }));

		// Indicate in status message
		this._notificationService.status(this.getStatusMessage(extensionName, workspaceFoldersToAdd.length, deleteCount), { hideAfter: 10 * 1000 /* 10s */ });

		return this._workspaceEditingService.updateFolders(index, deleteCount, workspaceFoldersToAdd, true);
	}