public boolean contains(OWLDataProperty prop) {
   if (prop.equals(owlOntologyManager.getOWLDataFactory().getOWLThing())) {
     return true;
   } else if (prop.equals(owlOntologyManager.getOWLDataFactory().getOWLNothing())) {
     return true;
   }
   return owlDataProperty2DataPropertyPointerMap.containsKey(prop);
 }
 public void visit(OWLDataProperty owlDataProperty) {
   try {
     lastDataPropertyPointer = owlDataProperty2DataPropertyPointerMap.get(owlDataProperty);
     if (lastDataPropertyPointer == null) {
       lastDataPropertyPointer = faCTPlusPlus.getDataProperty(owlDataProperty.getURI().toString());
       dataPropertyPointerMap.put(lastDataPropertyPointer, owlDataProperty);
       owlDataProperty2DataPropertyPointerMap.put(owlDataProperty, lastDataPropertyPointer);
     }
   } catch (Exception e) {
     throw new FaCTPlusPlusRuntimeException(e);
   }
 }