internal void Complete(HttpListenerContext context, bool syncCompleted)
        {
            HttpListener listener = context.Listener;

            if (!listener.Authenticate(context))
            {
                listener.BeginGetContext(this);
                return;
            }
            _context       = context;
            _syncCompleted = syncCompleted;
            lock (_sync)
            {
                complete(this);
            }
        }