Если я правильно понял ваш вопрос и Java API, на который вы ссылаетесь, это OWL API , это должно сработать:
/*Load your ontology from a local file and do the initialisations*/
File inputfile = new File("ontologyPath");
OWLOntologyManager manager = OWLManager.createOWLOntologyManager(); ;
OWLDataFactory dataFactory = manager.getOWLDataFactory();
OWLOntology yourOntology = manager.loadOntologyFromOntologyDocument(inputfile);
IRI ontologyIRI = yourOntology.getOntologyID().getOntologyIRI();
/*Get the object property and the individual you're interested in*/
OWLObjectProperty o_p_responsible_for = dataFactory.getOWLObjectProperty(IRI.create(ontologyIRI + "#"+"Responsiblefor"));
OWLIndividual ind_Wayne = dataFactory.getOWLNamedIndividual(IRI.create(ontologyIRI + "#"+"Wayne_Smith"));
/*return the value*/
Set<OWLIndividual> responsibilities_of_Wayne= ind_Wayne.getObjectPropertyValues(o_p_responsible_for, yourOntology);