I created a table in ppt with 1px solid border applied to all. but If you check the resulting image using POI, you can see that the border is double-lined. how to fix it?

for (XSLFSlide slide : ppt.getSlides()) {
    BufferedImage image = new BufferedImage(pageSize.width, pageSize.height, BufferedImage.TYPE_INT_RGB);
    Graphics2D graphics = image.createGraphics();

    graphics.setFont(gqmsFontFamilyProvider.getDefaultFont());

    slide.draw(graphics);
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    ImageIO.write(image, "png", baos);
    images.add(baos.toByteArray());

    graphics.dispose();
    baos.close();
}