Reading and writing a References<T>

ev.Sponsors.Ids;                        // Guid[] in stored order
ev.Sponsors.Count();
ev.Sponsors.Contains(organizerId);

ev.Sponsors.Add(organizerId);
ev.Sponsors.Add(organizer, db);
ev.Sponsors.Remove(organizerId);        // removes every occurrence
ev.Sponsors.Clear();
ev.Sponsors.Ids = [a, b, c];            // replace them all, in this order
db.Update(ev);

foreach (var sponsor in ev.Sponsors.Get())   // loads every target, in order
    Console.WriteLine(sponsor.Name);