This is an easy call. The answer is that it's not worth changing
because this would cause legacy to to start failing
...
and there is already a perfectly reasonable workaround.
I agree. I do think it's worth issuing warnings _by default_, and
turning this into _opt-out_ rather than _opt-in_.
It's easy to have this opinion for any given warning; for every warning,
there is _someone_ who thinks it should be turned up (if not all the way
to error.) But these decisions need to be made within a more coherent
strategy than "this bug pattern really bugs me". Otherwise, we set
`javac` on a path where its secondary mission is to be a mediocre static
analysis engine. Our preference is to leave that to tools whose
_primary_ mission is static analysis -- of which there are many, and
they are all going to be much better at it than `javac`, because `javac`
has a different primary mission.
