Webrev: http://cr.openjdk.java.net/~mchung/jdk9/webrevs/8174740/webrev.00/
jlink system modules plugin incorrectly assumes that ModuleDescriptor::packages returns an empty set if the ModulePackages attribute is not present and no packageFinder supplier is provided. That’s not the case when the module descriptor contains exports/open packages. This fixes how the plugin determines if ModulePackages attribute is present. Mandy [1] http://mail.openjdk.java.net/pipermail/jigsaw-dev/2017-February/011268.html
