Hi Jason/Tomaz, Early Access build for JDK 9 b51 <https://jdk9.java.net/download/> available on java.net, summary of changes are listed here <http://www.java.net/download/jdk9/changes/jdk9-b51.html> I'd also like to use this opportunity to point you to JEP 238: Multi-Version JAR Files [0], which is currently a Candidate JEP for JDK 9. It's goal is to extend the JAR file format to allow multiple, JDK release-specific versions of class files to coexist in a single file. An additional goal is to backport the run-time changes to JDK 8u60, thereby enabling JDK 8 to consume multi-version JARs. For a detailed discussion, please see the corresponding thread on the core-libs-dev mailing list. [1] Please keep in mind that a JEP in the Candidate state is merely an idea worthy of consideration by JDK Release Projects and related efforts; there is no commitment that it will be delivered in any particular release. Comments, questions, and suggestions are welcome on the corelibs-dev mailing list. (If you haven’t already subscribed to that list then please do so first, otherwise your message will be discarded as spam.) Rgds,Rory [0] http://openjdk.java.net/jeps/238 [1] http://mail.openjdk.java.net/pipermail/core-libs-dev/2015-February/031461... -- Rgds,Rory O'Donnell Quality Engineering Manager Oracle EMEA , Dublin, Ireland