private static void printActivityDiagramInfo(IActivityDiagram diagram)
            throws InvalidUsingException {
        System.out.println(String.format("ActivityDiagram Name: %s", diagram.getName()));
        IActivity activity = diagram.getActivity();
        IActivityNode[] activityNodes = activity.getActivityNodes();
        for (IActivityNode activityNode : activityNodes) {
            INodePresentation presentation = getPresentation(activityNode);
            Point2D location = getLocation(presentation);
            System.out.println(String.format("   %s (X:%f, Y:%f)", presentation.getLabel(),
                    location.getX(), location.getY()));
        }
    }

    private static Point2D getLocation(INodePresentation presentation) {
        if (presentation == null) {
            throw new IllegalArgumentException("presentation is null.");
        }
        return presentation.getLocation();
    }

    private static INodePresentation getPresentation(IActivityNode activityNode)
            throws InvalidUsingException {
        if (activityNode == null) {
            throw new IllegalArgumentException("action is null.");
        }
        return (INodePresentation) activityNode.getPresentations()[0];
    }