private Set<Individual> listObjectProperties(OntResource ontResource, ObjectProperty prop) {
   LinkedHashSet<Individual> results = new LinkedHashSet<>();
   try (ClosableIterable<RDFNode> props = iterate(ontResource.listPropertyValues(prop))) {
     for (RDFNode node : props) {
       if (!node.isResource() || !node.canAs(Individual.class)) continue;
       results.add(node.as(Individual.class));
     }
   }
   return results;
 }