Report a Server that is now stopped. 
Called by a Transport when a Server is stopped. The Transport is permitted to reclaim resources used by the DTLConnection only after this callback returns.
This callback must not be NULL.
- Parameters
- 
  
    | handler | The TransportHandler managing server. This must not be NULL. |  | server | The transport representation of the Server. This must not be NULL. |  | except | An exception for the closure/failure of the server, if any. NULL indicates it was a normal closure due to Stop() being called on the DTLServer. Otherwise, it must be a valid DOFErrorException describing the failure. |