Bug 31683 Show In doesn't work for class file in rt.jar
I20030611 - create Test project that uses Jar container - open NumberFormat.class - activate Show In... and choose Package Explorer Observe: NumberFormat.class doesn't get revealed.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/PackageExplorerContentProvider.java
/* (non-Javadoc)
	 * Method declared on IContentProvider.
	 */
	public void dispose() {
		super.dispose();
		JavaCore.removeElementChangedListener(this);
		fPackageFragmentProvider.dispose();
	}
	
	
	private boolean needsToDelegateGetChildren(Object element) {
		int type= -1;
		if (element instanceof IJavaElement)
			type= ((IJavaElement)element).getElementType();
		return (!fIsFlatLayout && (type == IJavaElement.PACKAGE_FRAGMENT || type == IJavaElement.PACKAGE_FRAGMENT_ROOT || type == IJavaElement.JAVA_PROJECT));
	}		
	public Object[] getChildren(Object parentElement) {
		Object[] children= NO_CHILDREN;
		try {
			if (parentElement instanceof IJavaModel) 
				return concatenate(getJavaProjects((IJavaModel)parentElement), getNonJavaProjects((IJavaModel)parentElement));
			if (parentElement instanceof ClassPathContainer)
				return getContainerPackageFragmentRoots((ClassPathContainer)parentElement);
				
			if (parentElement instanceof IProject) 
				return ((IProject)parentElement).members();
					
			if (needsToDelegateGetChildren(parentElement)) {
				Object[] packageFragments= fPackageFragmentProvider.getChildren(parentElement);
				children= getWithParentsResources(packageFragments, parentElement);