LVQ was hardcoded to use a specific message header as the key determining equivalence (qpid.LVQ_key)
Producers need to be explicitly coded to set that header (implying they need to know they are using an LVQ). Would prefer to use an application defined header as the key.
New configuration option added to allow the choice of LVQ key to be set per-queue (qpid.last_value_queue_key)
Users can choose an application defined header (with more real significance) as the basis for message replacement/update. Producers will be setting such headers anyway and are thus free from explicit alteration for LVQ.