These are warnings from your IDE, not warnings seen when building with Ant, right? Compiling with Ant generates no warnings for me. Perhaps we should add Checkstyle and/or FindBugs to the Ant compilation if we wish to raise the warning bar?
Also some of the unused fields are fields that should perhaps remain. For example, in DataFileReader the bug is that we're missing a 'getCount()' accessor, not that we have an unused field. And in Requestor and Responder, those local variables will soon be used by
AVRO-66, a patch we don't want to generate spurious conflicts with.
Removing unused imports seems fine, but rearranging imports can break other patches. Also, replacing a wildcard import with a non-wildcarded long-term makes future unused imports more likely for folks like me who do not use an IDE (unless we add an equivalent Checkstyle test). So, again, I'm hesitant to encourage periodic cleanups of this sort without automatic testing that's common to all developers.
If we add Checkstyle and/or FindBugs to Ant compilation, to be effective, we should fail tests if there are any warnings. Both support the suppression of warnings for specific files, if needed.