### Question:
QNamePropertyConverter { public static Optional<javax.xml.namespace.QName> dmnFromWB(final QName wb) { if (wb != null) { if (Objects.equals(wb, BuiltInType.UNDEFINED.asQName())) { return Optional.empty(); } return Optional.of(new javax.xml.namespace.QName(wb.getNamespaceURI(), wb.getLocalPart(), wb.getPrefix())); } else { return Optional.empty(); } }  static QName wbFromDMN(final javax.xml.namespace.QName qName, final DMNModelInstrumentedBase parent); static void setDMNfromWB(final QName qname,
                                    final Consumer<javax.xml.namespace.QName> setter); static Optional<javax.xml.namespace.QName> dmnFromWB(final QName wb); static String getDefaultNamespace(final DMNModelInstrumentedBase parent);  }### Answer:
@Test public void testDMNfromWBnull() { Optional<javax.xml.namespace.QName> dmn = QNamePropertyConverter.dmnFromWB(new QName(XMLConstants.NULL_NS_URI, BuiltInType.UNDEFINED.getName(), Namespace.FEEL.getPrefix())); assertThat(dmn).isEmpty(); }