public override Task InvokeAsync(IncommingEnvelopeContext context, Func <Task> next)
 {
     Debug.WriteLine("Received message from {0}", context.Envelope.Headers[HeaderKeys.Sender]);
     return(next());
 }
 public override Task InvokeAsync(IncommingEnvelopeContext context, Func <Task> next)
 {
     throw new NotImplementedException();
 }