/usr/share/java/jabref-plugin-oo.jar is in jabref-plugin-oo 0.9+ds-1ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/java/../jabref/plugins/net.sf.jabref.oo.ooplugin-0.9.jar
/usr/share/java/../jabref/plugins/net.sf.jabref.oo.ooplugin-0.9.jar