src/vs/platform/userDataSync/common/userDataSyncService.ts/UserDataSyncService/getMachineId
class UserDataSyncService:	async getMachineId(resource: SyncResource, syncResourceHandle: ISyncResourceHandle): Promise<string | undefined> {
		const result = await this.performSynchronizerAction(async synchronizer => {
			if (synchronizer.resource === resource) {
				const result = await synchronizer.getMachineId(syncResourceHandle);
				return result || null;
			}
			return undefined;
		});
		return result || undefined;
	}