API, TCK and RI can be built and used on Java 9 up to b174. b175 cause issues due to Maven plug-ins incompatible with the changed version format as of that release. But this shouldn't affect our own program code. Closing this issue as "Out of Date" as nothing really remains to be done here. In a future revision we'll explore how to improve support for JPMS, e.g. by allowing to pass a factory for method handles during bootstrap, so to all access of private members without the need for opening modules.