DataContractJsonSerializer deserialize stream

            var response = await httpClient.PostAsync(endpoint, new FormUrlEncodedContent(parameters));
            var result = await response.Content.ReadAsStreamAsync();

            var reader = new StreamReader(result);
            var str = reader.ReadToEnd();

            //if (response.Content != null && response.IsSuccessStatusCode)
            //{
            //    var ser = new DataContractJsonSerializer(typeof (OAuth2TokenResult));
            //    tokenResult = (OAuth2TokenResult) ser.ReadObject(responseContent);
            //}