title: ReadAsAsync in c# throwing error
body: <p>I am getting an error on 
      AuthTokenRS value = await response.Content.ReadAsAsync();
  The error message is:</p>
  
  <blockquote>
    <p>'HttpContent' does not contain a definition for 'ReadAsAsync' and no extension method 'ReadAsAsync' and no extension method 'ReadAsAsync' accepting a first argument of type 'HttpContent' could be found(are you missing a using directive or an assembly reference?).</p>
  </blockquote>
  
  <p>Here is my code snippet:</p>
  
  <pre><code>public async Task&lt;HttpResponse&lt;AuthTokenRS&gt;&gt; AuthorizeAsync(string credentials)
  {
      using (HttpClient client = new HttpClient())
      {
          client.BaseAddress = new Uri(this.config.Environment);
          client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", credentials);
          client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("*/*"));
  
          var args = new Dictionary&lt;string, string&gt;();
          args.Add("grant_type", "client_credentials");
          var content = new FormUrlEncodedContent(args);
          Logger.DebugFormat("POST {0}\n{1}", AuthorizationEndpoint, await content.ReadAsStringAsync());
  
          var response = await client.PostAsync(AuthorizationEndpoint, content);
          string requestUri = response.RequestMessage.RequestUri.ToString();
          if (response.IsSuccessStatusCode)
          {
              //AuthTokenRS value = await response.Content.ReadAsAsync&lt;AuthTokenRS&gt;();
              AuthTokenRS value = await response.Content.ReadAsAsync&lt;AuthTokenRS&gt;();
  
              return HttpResponse&lt;AuthTokenRS&gt;.Success(response.StatusCode, value, requestUri);
          }
          else
          {
              return HttpResponse&lt;AuthTokenRS&gt;.Fail(response.StatusCode, await response.Content.ReadAsStringAsync(), requestUri);
          }
      }
  }
  </code></pre>