Improve handling of disconnect events in STOMP broker relay [SPR-11655] #16278
Description
Rossen Stoyanchev opened SPR-11655 and commented
It is possible for messages to be forwarded around the same time when the connection to the broker is lost (e.g. broker is shut down) or after a DISCONNECT is sent to the broker and the connection is in the process of being closed.
Such messages may fail in a couple of ways, either the forward fails or the connection becomes null leading to a NPE. The exceptions and messages are expected and harmless but cause alarm.
The logic can be refined to better handle this situation and avoid error messages for cases where we know it's not really an error.
Affects: 4.0.3