如何更改owl api中已有的OWLDataPropertyAssertionAxiom值？

OWLOntologyManager manager = OWLManager.createOWLOntologyManager();
OWLOntology ontology = manager.createOntology();

Set<OWLDataPropertyAssertionAxiom> axioms = ontology.getAxioms(AxiomType.DATA_PROPERTY_ASSERTION);

OWLDataFactory factory = manager.getOWLDataFactory();
OWLDataPropertyAssertionAxiom axiomToChange = null;
for (OWLDataPropertyAssertionAxiom axiom : axioms) {
    if (axiom.getProperty().equals(factory.getOWLDataProperty(IRI.create("http://example.com#propertyName")))) {
        axiomToChange = axiom;
        break;
    }
}

OWLDataPropertyAssertionAxiom newAxiom = factory.getOWLDataPropertyAssertionAxiom(
        axiomToChange.getProperty(),
        axiomToChange.getSubject(),
        factory.getOWLLiteral("new value"));

manager.removeAxiom(ontology, axiomToChange);
manager.addAxiom(ontology, newAxiom);