Unless the "final" qualifiers are required as part of this improvement, say to better inform the GC of what can be changed, then I'd suggest separating them out into separate commits. That way the lines that improves the hashCode() method and switches to using CompoundCacheKey stand out as the real changes.
I had a similar experience helping with the H2 database engine.
thanks for trying to report the issue. Do you have a bug ID for the item you're referring to? Searching for the title doesn't show me an issue. In general we try to react to all reports, unfortunately sometimes some are missed or wrongly categorized due to the big overall inflow.
johannes (MySQL Connectors team, but not working on Java and without deeper Java knowledge)
edit: Well actually the recent edit makes this comment now more confusing. The github page is associated with a MySQL bug, which will be handled. This comment, originally, was under a different thread, which, to me, sounded like there was another bug report by dang we missed ...