src/vs/workbench/services/workingCopy/common/workingCopyBackupService.ts/WorkingCopyBackupsModel/add
class WorkingCopyBackupsModel:	add(resource: URI, versionId = 0, meta?: IWorkingCopyBackupMeta): void {
		this.cache.set(resource, { versionId, meta: deepClone(meta) }); // make sure to not store original meta in our cache...
	}