Modifier un PDF en Java

Presentation pres = new Presentation();
try {
    pres.getSlides().removeAt(0);
    pres.getSlides().addFromPdf("document.pdf");

    ISlide slide = pres.getSlides().get_Item(0);
    IAutoShape shape = slide.getShapes().addAutoShape(ShapeType.Rectangle, 10, 10, 100, 50);
    shape.getTextFrame().setText("New text");

    pres.save("document.pdf", SaveFormat.Pdf);
} finally {
    if (pres != null) pres.dispose();
}