تبدیل PPTX به Word در جاوا

Presentation pres = new Presentation(inputPres);
try {
    Document doc = new Document();
    DocumentBuilder builder = new DocumentBuilder(doc);
    for (ISlide slide : pres.getSlides())
    {
        // generates and inserts slide image
        BufferedImage bitmap = slide.getThumbnail(1, 1);

        builder.insertImage(bitmap);

        // inserts slide's texts
        for (IShape shape : slide.getShapes())
        {
            if (shape instanceof AutoShape)
            {
                builder.writeln(((AutoShape)shape).getTextFrame().getText());
            }
        }

        builder.insertBreak(BreakType.PAGE_BREAK);
    }
    doc.save(outputDoc);
} finally {
    if (pres != null) pres.dispose();
}