A panel in a nested document won't be registered at startup

            Query query =
                queryManager.createQuery("select doc.space, doc.name from Document doc, doc.object(Panels.PanelClass) "
                    + "as panel", Query.XWQL);
            List<Object[]> results = query.execute();
            for (Object[] result : results) {
                references.add(
                    new DocumentReference(getXWikiContext().getWikiId(), (String) result[0], (String) result[1]));
            }