eclipse-osgi ebuild has a typo. Instead of 'javadoc' target there is 'javaodc'.
There appear to be two typos. After correcting the javadoc I ran it with USE="doc" and it tried to install the docs to ${S}/${OSGI_PLUGIN}/dist/docs/ After looking in the /var/tmp/portage work for this package I see a "dist/doc" (not docs). After changing that, doing a new digest eclipse-osgi installs properly.
Created attachment 80853 [details] ebuild with typo's fixed. This is the ebuild I corrected and used to install eclipse-osgi-3.2_pre2.
Sorry for taking so long with this. This has been fixed in portage. Please sync and test in ~2 hours.