private void Handle(FeedDataSourceSubscribedEvent evt)
{
if (UserId != evt.UserId)
{
throw new DomainException(Global.UserNotAuthorizedToSubscribe);
}
if (DataSources.Any(d => d.DatasourceId == evt.DataSourceId))
{
throw new DomainException(string.Format(Global.DatasourceAlreadyExists, evt.DataSourceId));
}
DataSources.Add(FeedDatasource.Create(evt.DataSourceId));
UpdateDateTime = evt.CreateDateTime;
Version = evt.Version;
}