Workaround for bug in Jena OntTools.namedHierarchyRoots

gistfile1.java

package usertests;

import java.io.StringReader;
import java.util.Iterator;

import com.hp.hpl.jena.ontology.*;
import com.hp.hpl.jena.rdf.model.ModelFactory;
import com.hp.hpl.jena.util.iterator.ExtendedIterator;

public class LHRTest
{
    public static final String SOURCE = "<?xml version=\"1.0\"?>\n" +
            "<rdf:RDF\n" +
            "    xmlns:rdf=\"http://www.w3.org/1999/02/22-rdf-syntax-ns#\"\n" +
            "    xmlns:rdfs=\"http://www.w3.org/2000/01/rdf-schema#\"\n" +
            "    xmlns:owl=\"http://www.w3.org/2002/07/owl#\" >\n" +
            "<owl:Class rdf:about=\"http://dbpedia.org/class/yago/Album106591815\"/>\n" +
            "<owl:Class rdf:about=\"http://dbpedia.org/class/yago/HostCitiesOfTheCommonwealthGames\"/>\n" +
            "<owl:ObjectProperty rdf:about=\"http://dbpedia.org/property/after\">      \n" +
            "<rdfs:domain>\n" +
            "<owl:Class>\n" +
            "<owl:unionOf rdf:parseType=\"Collection\">\n" +
            "<owl:Class rdf:about=\"http://dbpedia.org/class/yago/Album106591815\"/>\n" +
            "</owl:unionOf>\n" +
            "</owl:Class>\n" +
            "</rdfs:domain>\n" +
            "</owl:ObjectProperty>\n" +
            "</rdf:RDF>";

    public static void main( String[] args ) {
        OntModel m = ModelFactory.createOntologyModel( OntModelSpec.OWL_MEM_MICRO_RULE_INF );
        m.read( new StringReader( SOURCE ), "RDF/XML" );

        for (ExtendedIterator<OntClass> i = m.listHierarchyRootClasses(); i.hasNext(); ) {
            System.out.println( "LHRC -> " + i.next() );
        }

        OntModel base = ModelFactory.createOntologyModel( OntModelSpec.OWL_MEM, m.getBaseModel() );
        for (Iterator<OntClass> i = OntTools.namedHierarchyRoots( base ).iterator(); i.hasNext(); ) {
            System.out.println( "NHR -> " + i.next() );
        }
    }

}

Output:

LHRC -> 3788676f:1389f06e9d6:-7ffc
LHRC -> http://dbpedia.org/class/yago/HostCitiesOfTheCommonwealthGames
NHR -> http://dbpedia.org/class/yago/HostCitiesOfTheCommonwealthGames
NHR -> http://dbpedia.org/class/yago/Album106591815