protected override Task <HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) { if (ResponseUtils.IsNegotiateRequest(request)) { return(Task.FromResult(ResponseUtils.CreateResponse(HttpStatusCode.OK, ResponseUtils.CreateNegotiationResponse()))); } else { return(Task.FromException <HttpResponseMessage>(new InvalidOperationException($"Http endpoint not implemented: {request.RequestUri}"))); } }