private async Task DeleteAppointment (AppointmentItemWrapper item, Dictionary<AppointmentId, IEntityRelationData<AppointmentId, DateTime, WebResourceName, string>> relations)
{
IEntityRelationData<AppointmentId, DateTime, WebResourceName, string> relation;
var appointmentId = new AppointmentId(item.Inner.EntryID, item.Inner.GlobalAppointmentID);
if (relations.TryGetValue (appointmentId, out relation))
{
await _btypeRepository.TryDelete (relation.BtypeId, relation.BtypeVersion, NullEventSynchronizationContext.Instance);
relations.Remove (appointmentId);
}
item.Inner.Delete();
}