Do you do any Z-Wave driver development? Hubitat recommends using a couple static field variables to handle Supervision: [GUIDE] Writing Z-Wave Drivers for S2
I've seen some people complain of errors that look like concurrency issues, which I see that the 2.2.8 release notes note a fix for:
C7: Fixed concurrency error produced on some Z-Wave drivers when using S2 and Supervision.
However, I'm curious what the fix was...switching to ConcurrentHashMap instead of the default Map, maybe? 
In any case, that is a practical example where this matters--not only could Hubitat could get two Z-Wave reports back from the device in quick succession (while the first instance of the driver does not finish executing before the second begins), but static fields are shared among all devices that use the driver, not just one particular installed instance--hence the reason these are static Maps indexed by device ID (which if someone could tell me why they recommend converting that to a String instead of the actual Long type, I'd be interested in knowing, but that's unrelated...). So, if two devices (using the same driver) just get a single report back at nearly the same time, the same concern applies.
(If ConcurrentHashMap was the fix, I don't see that mentioned anywhere and definitely not in the above. Might be worth asking, unless this was some platform-level change, but the "some drivers" phrasing doesn't sound like it. Probably worth asking in that other thread...)
