Upload file with form data

gistfile1.cs

using (var content = new MultipartFormDataContent())
{
  //hackety hack hack hack
  //this will throw if object has complex/nested properties
   var messageAsKeyValuePairs = JsonConvert.DeserializeObject<IDictionary<string, string>>(JsonConvert.SerializeObject(message));

   foreach (var kvp in messageAsKeyValuePairs.Where(kvp => kvp.Value != null))
   {
     content.Add(new StringContent(kvp.Value), kvp.Key);
   }

   var streamContent = new StreamContent(source);
   streamContent.Headers.Clear();
   streamContent.Headers.Add("Content-Type", "application/octet-stream");
   streamContent.Headers.Add("Content-Disposition", "form-data; name=\"file\"; filename=\"" + fileName + "\"");
   content.Add(streamContent, "file", fileName);

   var response = await client.PostAsync(requestUrl, content);
   return await response.Content.ReadAsAsync<TReturn>();
}