Buscar texto en PPTX con Java

Presentation presentation = new Presentation("welcome-to-powerpoint.pptx");
try {
    String searchText = "PowerPoint";

    for (ISlide slide : presentation.getSlides()) {
        ITextFrame[] slideTextFrames = SlideUtil.getAllTextBoxes(slide);

        for (ITextFrame textFrame : slideTextFrames) {
            for (IParagraph paragraph : textFrame.getParagraphs()) {
                for (IPortion portion : paragraph.getPortions()) {
                    if (portion.getText().contains(searchText)) {
                        System.out.println(portion.getText());
                    }
                }
            }
        }
    }
} finally {
    presentation.dispose();
}