src/vs/platform/userDataSync/common/abstractSynchronizer.ts/AbstractSynchroniser/getMachineId
class AbstractSynchroniser:	async getMachineId({ uri }: ISyncResourceHandle): Promise<string | undefined> {
		const ref = this.extUri.basename(uri);
		if (this.extUri.isEqual(uri, this.toRemoteBackupResource(ref))) {
			const { content } = await this.getUserData(ref);
			if (content) {
				const syncData = this.parseSyncData(content);
				return syncData?.machineId;
			}
		}
		return undefined;
	}