Bug 287103 [CommonNavigator] contentServiceLabelProvider doesn't properly implement overrides
tests/org.eclipse.ui.tests.navigator/src/org/eclipse/ui/tests/navigator/PipelineTest.java
public PipelineTest() {
		_navigatorInstanceId = TEST_VIEWER_PIPELINE;
	}
	public void testNavigatorRootContents() throws Exception {
		assertEquals(
				"There should be no visible extensions for the pipeline viewer.",
				0, _contentService.getVisibleExtensionIds().length);
		_contentService.bindExtensions(new String[] {
				COMMON_NAVIGATOR_RESOURCE_EXT, COMMON_NAVIGATOR_JAVA_EXT },
				false);
		
		
		assertEquals(
				"There should be two visible extensions for the pipeline viewer.",
				2, _contentService.getVisibleExtensionIds().length);
		_contentService.getActivationService().activateExtensions(
				new String[] { COMMON_NAVIGATOR_RESOURCE_EXT,
						COMMON_NAVIGATOR_JAVA_EXT }, true);
		refreshViewer();
		
		_viewer.setSelection(
				new StructuredSelection(_project.getFile(".project")), true); 
		TreeItem[] rootItems = _viewer.getTree().getItems();
		assertEquals("There should be one item.", _projectCount, rootItems.length); 		
		assertTrue(
				"The root object should be an IJavaProject, which is IAdaptable.", rootItems[0].getData() instanceof IAdaptable);