On shutting down the broker, the connection state of active connections is not freed

The IO layer (e.g. AsynchIOHandler for TCP) creates and holds a ConnectionCodec object by pointer for each connection. All connection state is rooted in that object. However for connections that are active when the broker is shutdown, those objects and all their internal state, is not freed but is leaked.

As the broker is shutting down anyway, the leak is not nice but not critical (henc I've marked this as minor rather than major). However it can lead to e.g. Queue destructors not being called etc.