public virtual void LinkToUserRoomMembership(UserRoomMembership userRoomMembership)
{
if (userRoomMembership == null)
{
throw new ArgumentNullException(nameof(userRoomMembership));
}
if (UserRoomMembership != null)
{
throw new InvalidOperationException("UserRoomMembership is already set.");
}
UserRoomMembership = userRoomMembership;
}