I don't think eclass/java-utils-2 should add a runtime dependency on portage as not every java package invokes portage itself during runtime. I found this while trying to set up an embedded system which doesn't need to have portage installed. Reproducible: Always
java-config depends on Portage at runtime. This dependency is currently implicit, so can't drop Portage in the eclass without adding it to java-config. package.provided may work for you (see portage(5)) but you are on your own. Long term dropping Portage is desirable as ideally java-config would be portable to other distros and OSs. Once EAPI 0 & 1 java packages are gone from tree, the build dependency on Portage in the eclass can be dropped as well.
*** Bug 533510 has been marked as a duplicate of this bug. ***
Fixed. The dependency was added to java-config a while back.