void OnUserRemoved(object sender, UserEventArgs e)
{
participants.Remove(GetParticipant(e.User));
UserRemoved.SafeInvoke(this, e);
if (participants.Count == 0)
{
Ended.SafeInvoke(this, new EventArgs());
events.UserAdded -= OnUserAdded;
events.UserChanged -= OnUserChanged;
events.UserRemoved -= OnUserRemoved;
events.UserTyping -= OnUserTyping;
events.ChatReceived -= OnChatReceived;
}
}