This is the eclipse osgi package. It is a part of eclipse, and is built as a seperate package for building of jface and jdtcore packages. This ebuild was done by qian.qiao@gmail.com in bug #71856.
Created attachment 50969 [details] eclipse-osgi-3.0.1.ebuild
Since this is a pretty radical change, I've committed it to the experimental tree for now. Go see: https://gentooexperimental.org/svn/java/gentoo-java-experimental/dev-eclipse/eclipse-osgi/