public void AddParticipant(EventParticipant eventParticipant)
{
if (EventParticipants.Contains(eventParticipant))
{
throw new ApplicationException($"添加错误：参与者已存在！");
}
EventParticipants.Add(eventParticipant);
}
public void RemoveParticipant(EventParticipant eventParticipant)
{
EventParticipants.Remove(eventParticipant);
}
