    @Test
    public void testUpgradeXmlNamespace() {

        try {
            Document doc = buildTransferDocumentForUpgrade();
            Element root;
            String ns;

            //System.out.println( "----------------------------" );
            //System.out.println( "DOCUMENT BEFORE CONVERSION:" );
            //DocumentUtils.write( doc, System.out );
            //System.out.println( "----------------------------" );

            root = XmlUtils.getRootElement(doc);
            ns = (root != null) ? StringUtils.trimToEmpty(root.getNamespaceURI()) : null;
            Assert.assertEquals(
                    "XML namespace before conversion.", OpenImmoUtils.OLD_NAMESPACE, ns);

            new OpenImmo_1_2_1().upgradeXmlNamespace(doc);

            //System.out.println( "----------------------------" );
            //System.out.println( "DOCUMENT AFTER CONVERSION:" );
            //DocumentUtils.write( doc, System.out );
            //System.out.println( "----------------------------" );

            root = XmlUtils.getRootElement(doc);
            ns = (root != null) ? StringUtils.trimToEmpty(root.getNamespaceURI()) : null;
            Assert.assertEquals(
                    "XML namespace after conversion.", StringUtils.EMPTY, ns);
        } catch (Exception ex) {
            LOGGER.error("Test of OpenImmo_1_2_1.upgradeXmlNamespace failed!");
            LOGGER.error("> " + ex.getLocalizedMessage(), ex);
            Assert.fail("Test of OpenImmo_1_2_1.upgradeXmlNamespace failed!");
        }
    }