如何使用owlapi 5.1检索OWL类的子类？

<dependency>
    <groupId>net.sourceforge.owlapi</groupId>
    <artifactId>owlapi-distribution</artifactId>
    <version>5.1.12</version>
</dependency>

OWLOntologyManager manager = OWLManager.createOWLOntologyManager();

File ontologyFile = new File("path/to/ontology.owl");
OWLOntology ontology = manager.loadOntologyFromOntologyDocument(ontologyFile);

OWLDataFactory dataFactory = manager.getOWLDataFactory();
OWLClass owlClass = dataFactory.getOWLClass(IRI.create("http://example.com#MyClass"));

Set<OWLClassExpression> subClasses = owlClass.getSubClasses(ontology);
for (OWLClassExpression subClass : subClasses) {
    System.out.println(subClass.asOWLClass().getIRI().getFragment());
}