public static IObservable <TokenCacheNotificationArgs> SynchStorage(this ITokenCache tokenCache, string cacheFilePath)
 => tokenCache.ReadStorage(cacheFilePath).Merge(tokenCache.WriteStorage(cacheFilePath));
 public static IObservable <TokenCacheNotificationArgs> SynchStorage(this ITokenCache tokenCache, Func <IObjectSpace> objectspaceFactory, Guid userId)
 => tokenCache.ReadStorage(objectspaceFactory, userId).Merge(tokenCache.WriteStorage(objectspaceFactory, userId));