LockedConnection provides access to the underlying Connection via alias
this. And the alias this means LockedConnection can be implicitly
converted to the underlying Connection.
Am I correct in understanding that means it's possible for a
LockedConnection to go out of scope and become re-locked, but then
something that was already holding a reference to its underlying
Connection now has an "illegal" reference to a connection that's been
returned to the pool?
I take it this is something for user code to be careful to avoid?