src/vs/platform/backup/electron-main/backupMainService.ts/BackupMainService/registerEmptyWindowBackupSync
class BackupMainService:	registerEmptyWindowBackupSync(backupFolderCandidate?: string, remoteAuthority?: string): string {

		// Generate a new folder if this is a new empty workspace
		const backupFolder = backupFolderCandidate || this.getRandomEmptyWindowId();
		if (!this.emptyWindows.some(emptyWindow => !!emptyWindow.backupFolder && this.backupPathComparer.isEqual(emptyWindow.backupFolder, backupFolder))) {
			this.emptyWindows.push({ backupFolder, remoteAuthority });
			this.saveSync();
		}

		return this.getBackupPath(backupFolder);
	}