Bug 15301 'show in packages view' - does not work fo java files not in source folders
20020502 open a java file that is in a resource folder (so it is not an ICompilationUnit - just a file with .java extension) 'show in packages view' is present in the context menu but it does nothing
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/viewsupport/BaseJavaElementContentProvider.java
}
	protected boolean isProjectPackageFragmentRoot(IPackageFragmentRoot root) throws JavaModelException {
		IResource resource= root.getUnderlyingResource();
		return (resource instanceof IProject);
	}
	
	protected boolean exists(Object element) {
		if (element == null) {
			return false;
		}
		if (element instanceof IResource) {
			return ((IResource)element).exists();
		}
		if (element instanceof IJavaElement) {
			return ((IJavaElement)element).exists();
		}
		return true;
	}
	
	protected Object internalGetParent(Object element) {
		if (element instanceof IJavaProject) {
			return ((IJavaProject)element).getJavaModel();
		}
		
		if (element instanceof IResource) {
			IResource parent= ((IResource)element).getParent();
			Object packageFragment= JavaCore.create(parent);
			if (packageFragment != null) 
				return packageFragment;
			return parent;