public Task Execute(StartScan c) => repository.Execute(c.HappeningId, h => h.ValidateStartScan(c.ToScanInfo()));
public Task Execute(UnlinkPersonFromHappening c) => // Validate first, PersonMessageHandler takes care of the next step happeningsRepository.Execute( RootAggregateId, h => h.ValidatePersonUnlink(c.HappeningId, c.PersonId));