@Test
public void getDatatypeXsIntEmpty() throws ValidationException {

    QName xsInt= new QName(DatatypeFactory.NS_XSD, "xs:int?");
    Datatype intDT = instance.getDatatype(xsInt);
    assertTrue("xs:int? does not allow empty sequence", intDT.allowsEmpty());
    assertFalse("xs:int? allows multiple values", intDT.allowsMultiple());
    XdmValue ret = intDT.convert("4", saxonConfiguration);
    assertTrue("value is not a XdmAtomicValue", ret instanceof XdmAtomicValue);
    ret = intDT.convert(null, saxonConfiguration);
    assertEquals("value is not an empty sequence", 0, ret.size());
}