When Copper receive a non-confirmable observe notification from the server , it does return an empty acknowledge message that contain the token of the original request.
An empty message should not contain a token.
From RFC7252 section 1.2-->
Empty Message
A message with a Code of 0.00; neither a request nor a response.
An Empty message only contains the 4-byte header.
Also in section 2.2 of the RFC, in the Request/Response examples, the empty acknowledge messages only contain the message id, no token.
When Copper receive a non-confirmable observe notification from the server , it does return an empty acknowledge message that contain the token of the original request. An empty message should not contain a token.
From RFC7252 section 1.2-->
Empty Message A message with a Code of 0.00; neither a request nor a response. An Empty message only contains the 4-byte header.
Also in section 2.2 of the RFC, in the Request/Response examples, the empty acknowledge messages only contain the message id, no token.
here is the current behavior-->