.net core static httpclient async send multiple requests with auth token

net core httpclient.md

Do NOT set client/request specific headers (auth) on the (static) HttpClient object, set them on the HttpRequest https://stackoverflow.com/questions/37928543/httpclient-single-instance-with-different-authentication-headers

https://docs.microsoft.com/en-us/aspnet/web-api/overview/advanced/calling-a-web-api-from-a-net-client

https://aspnetmonsters.com/2016/08/2016-08-27-httpclientwrong/

ProcessUrlListController.cs

private static HttpClient client = new HttpClient();

// send off reqs as fast as possible, then process them, arbitrary Item's, each having a Url to process
public async Task<ActionResult> ProcessUrlList(List<Item> items, string token)
{
  var reqs = new List<Task<HttpResponseMessage>>();
  foreach(var item in items)
  {
    reqs.Add(Req(item.Url, token));
  }
  foreach(var req in reqs)
  {
    var resolved = await Resolve(req);
    // process content of object returned from Resolve
  }
  return ProcessedContent; // psuedo
}

public Task<HttpResponseMessage> Req(string url, string token)
{
  var httpRequestMessage = new HttpRequestMessage(HttpMethod.Get, url);
  httpRequestMessage.Headers.Authorization = new AuthenticationHeaderValue("Bearer", token);
  return client.SendAsync(httpRequestMessage);
}

// return custom ResponseObject 
public async Task<ResponseObject> Resolve(Task<HttpResponseMessage> responseMessage)
{
    var response = await responseMessage;
    using (var reader = new StreamReader(await response.Content.ReadAsStreamAsync()))
    {
       var body = await reader.ReadToEndAsync();
       // process body
    }
    // build custom ResponseObject ...
}