I've put together this patch (over 9.1-902, which is just what I currently use), if anybody's interested: http://pastebin.com/KftdtdNq ,but:
- it uses JDK6 stuff
- has effect of copying all statements/resultset warnings into connection warnings
And one other thing. That's not asynchronous, it simply provides callbacks into the caller's app to allow to process notifications as they are received.