public Task <SourceSubscription> AddSubscriptionAsync(SourceSubscription subscription)
 {
     return(TryCatch(async() =>
     {
         ValidateSubscriptionOnAdd(subscription);
         subscription.Id = 0;
         var storageSubscription = await _storageBroker.InsertSourceSubscriptionAsync(subscription);
         await UpdateSubscriptionVacanciesAsync(storageSubscription);
         return storageSubscription;
     }));
 }