FlickrNet.FlickrResponder.GetDataResponseOAuthAsync C# (CSharp) Méthode

        private static async Task<FlickrResult<string>> GetDataResponseOAuthAsync(Flickr flickr, string hashCall, string baseUrl, Dictionary<string, string> parameters)
        {
            string method = "POST";

            // Remove api key if it exists.
            if (parameters.ContainsKey("api_key")) parameters.Remove("api_key");
            if (parameters.ContainsKey("api_sig")) parameters.Remove("api_sig");

            // If OAuth Access Token is set then add token and generate signature.
            if (!String.IsNullOrEmpty(flickr.OAuthAccessToken) && !parameters.ContainsKey("oauth_token"))
            {
                parameters.Add("oauth_token", flickr.OAuthAccessToken);
            }
            if (!String.IsNullOrEmpty(flickr.OAuthAccessTokenSecret) && !parameters.ContainsKey("oauth_signature"))
            {
                string sig = flickr.OAuthCalculateSignature(method, baseUrl, parameters, flickr.OAuthAccessTokenSecret);
                parameters.Add("oauth_signature", sig);
            }

            // Calculate post data, content header and auth header
            string data = OAuthCalculatePostData(parameters);
            string authHeader = OAuthCalculateAuthHeader(parameters);

            // Download data.
            try
            {
                return  await DownloadDataAsync(method, hashCall, baseUrl, data, PostContentType, authHeader);
            }
            catch (WebException ex)
            {
                //if (ex.Status != WebExceptionStatus.ProtocolError) throw;
                Debug.WriteLine("ERR - [" + baseUrl + "] " + ex.Message);
                HttpWebResponse response = ex.Response as HttpWebResponse;
                if (response == null) throw;

                if (response.StatusCode != HttpStatusCode.BadRequest && response.StatusCode != HttpStatusCode.Unauthorized) throw;

                using (StreamReader responseReader = new StreamReader(response.GetResponseStream()))
                {
                    string responseData = responseReader.ReadToEnd();
                    

                    throw new OAuthException(responseData, ex);
                }
            }

            //return null;
        }