Bug 60349 [implementation] reduce warnings due to core.runtime deprecations
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/ClasspathContainerDescriptor.java
private IClasspathContainerPage fPage;
	private static final String ATT_EXTENSION = "classpathContainerPage"; 
	private static final String ATT_ID = "id"; 
	private static final String ATT_NAME = "name"; 
	private static final String ATT_PAGE_CLASS = "class"; 	
	public ClasspathContainerDescriptor(IConfigurationElement configElement) throws CoreException {
		super();
		fConfigElement = configElement;
		fPage= null;
		String id = fConfigElement.getAttribute(ATT_ID);
		String name = configElement.getAttribute(ATT_NAME);
		String pageClassName = configElement.getAttribute(ATT_PAGE_CLASS);
		if (name == null) {
			throw new CoreException(new Status(IStatus.ERROR, JavaUI.ID_PLUGIN, 0, "Invalid extension (missing name): " + id, null)); 
		}
		if (pageClassName == null) {
			throw new CoreException(new Status(IStatus.ERROR, JavaUI.ID_PLUGIN, 0, "Invalid extension (missing page class name): " + id, null)); 
		}
	}
	public IClasspathContainerPage createPage() throws CoreException  {
		if (fPage == null) {
			Object elem= CoreUtility.createExtension(fConfigElement, ATT_PAGE_CLASS);
			if (elem instanceof IClasspathContainerPage) {
				fPage= (IClasspathContainerPage) elem;
			} else {
				String id= fConfigElement.getAttribute(ATT_ID);
				throw new CoreException(new Status(IStatus.ERROR, JavaUI.ID_PLUGIN, 0, "Invalid extension (page not of type IClasspathContainerPage): " + id, null)); 
			}
		}
		return fPage;