Covariant overrides on the Buffer Hierarchy redux

Hi, There was discussion here: http://mail.openjdk.java.net/pipermail/core-libs-dev/2014-April/026458.html https://bugs.openjdk.java.net/browse/JDK-4774077 http://cr.openjdk.java.net/~rwarburton/buffer-overrides-1/ The patch looks good. I have just one comment: can you check the tests to see if there are any redundant casts? After that i will run a JPRT test and then will push for you. Thanks, Paul.