Version 7.0.0 not working with os httphandlers

[lukapor]

If I am using
AppContext.SetSwitch("System.Net.Http.UseSocketsHttpHandler", false);
with version 7.0.0 at least Indices api Exists doesnt work correctly. if I am using 7.0.0-beta1 everything is ok.

Here is code to reproduce
static void Main(string[] args)
{
AppContext.SetSwitch("System.Net.Http.UseSocketsHttpHandler", false);
var defaultIndex = "nonexist_index";
var pool = new SingleNodeConnectionPool(new Uri("http://localhost:9210"));

var settings = new ConnectionSettings(pool)
    .DefaultIndex(defaultIndex)
    .DisableDirectStreaming()
    .PrettyJson();

var client = new ElasticClient(settings);

var response = client.Indices.Exists(defaultIndex);
if (response.ApiCall.HttpStatusCode != (int)HttpStatusCode.NotFound)
   throw new Exception("Should be 404 status code.");

}

[russcam]

Thanks for opening @lukapor, we'll need to investigate.

[russcam]

I can replicate an issue. The HttpStatusCode is null in this scenario, and an exception has been thrown, which can be viewed on response.OriginalException

System.Net.Http.HttpRequestException: An error occurred while sending the request. ---> System.Net.Http.WinHttpException: Error 87 calling WinHttpSendRequest, 'The parameter is incorrect'.
   at System.Net.Http.WinHttpException.ThrowExceptionUsingLastError(String nameOfCalledFunction)
   at System.Net.Http.WinHttpHandler.InternalSendRequestAsync(WinHttpRequestState state)
   at System.Net.Http.WinHttpHandler.StartRequest(WinHttpRequestState state)
   --- End of inner exception stack trace ---
   at System.Net.Http.HttpClient.FinishSendAsyncUnbuffered(Task`1 sendTask, HttpRequestMessage request, CancellationTokenSource cts, Boolean disposeCts)
   at Elasticsearch.Net.HttpConnection.Request[TResponse](RequestData requestData)

This occurs when making the request, and before a HTTP request is actually sent.

[russcam]

My initial suspicion here is that this relates to the introduction of RequestDataContent in a525ac8, which is used instead of StreamContent.

/cc @Mpdreamz

[russcam]

opened #3925 to address

[russcam]

This will be fixed in the next release