### Question:
UpgradeHandler_V9 implements UpgradeHandler { @Override public void processProjectDom(UpgradeUnit upgradeUnit) { Element domain = upgradeUnit.getDocument().getDocumentElement(); domain.setAttribute("project-version", getVersion()); }  @Override String getVersion(); @Override void processProjectDom(UpgradeUnit upgradeUnit); @Override void processDataMapDom(UpgradeUnit upgradeUnit);  }### Answer:
@Test public void testProjectDomUpgrade() throws Exception { Document document = processProjectDom("cayenne-project-v8.xml"); Element root = document.getDocumentElement(); assertEquals("9", root.getAttribute("project-version")); assertEquals("", root.getAttribute("xmlns")); assertEquals(2, root.getElementsByTagName("map").getLength()); }