Updated
Take http://bugs.sun.com/view_bug.do?bug_id=6857057. We witnessed this in JRE 6u17. How do I know which version of the JRE contains the fix? The general consensus on the Internet seems to be 6u18 - but how can I tell this from the bug database? It says fixed in 6u16-rev, but I don't know what '-rev' means. Also it says it still affects version 6u18 - so is there some time dilation going on?
Note
Originally I assumed I'd need to build against a newer version of the JDK, so asked how I'd know which version of the JDK contained the fix. I've updated the question based on mindas explaining its actually the JRE which contains the fix.