It should be fine in most of the cases to just use the system proxy settings.
If anyone has issues with this approach, we can still make the WebClient.Proxy setting configurable somehow.
sealed StringAttribute because it is only contains text as attribute
sealed SpotifyWebAPI class as it implements IDisposable
Changed Exception catching where the Exception is not used to ignore the Exception object
Removed Console.WriteLine("Exception: " + e.Message) int HttpProcessor.Process as it is a library function which might not be used in a console application