public static void AddDomainUser(Int32 domainId, LMUser user)
 {
     lock (_domainUsersTalkingStick)
     {
         if (_domainUsers.ContainsKey(domainId))
         {
             _domainUsers[domainId].Add(user);
         }
         else
         {
             _domainUsers.Add(domainId, new List <LMUser> {
                 user
             });
         }
     }
 }