Java 9 is not yet fully supported on Gentoo.
#--- END OF EXAMPLES ---
+# James Le Cuirot <chewi@gentoo.org> (17 Dec 2017)
+# Java 9 is not yet fully supported on Gentoo. Packages cannot depend
+# on it so these virtuals are not yet required. If you wish to use
+# Java 9 now then install oracle-(jdk|jre)-bin:9 directly.
+virtual/jdk:9
+virtual/jre:9
+
# Mike Gilbert <floppym@gentoo.org> (16 Dec 2017)
# Dev channel releases are only for people who are developers or want more
# experimental features and accept a more unstable release.