private void DisposeLocalUser()
 {
     if (_localUser is not null)
     {
         _localUser.Dispose();
         _localUser = null;
     }
 }
 public IUserConfig AddUser(string userID)
 {
     CheckUserID(userID);
     lock (this)
     {
         if (_localUser is not null)
         {
             throw new InvalidOperationException("Local user has already been created.");
         }
         _localUser = new MemoryUserConfig();
         return(_localUser);
     }
 }