Overlay PDF Docs

[Vorpahl,Lucinda]

I am hoping someone can help me.

I have a list of PDDocuments that I want to combine and draw onto 1 PDDocument.
I was able to do this by converting the individual documents to images then 
drawing the image on the new document but I lost image quality.
I was looking at the Overlay option but I'm getting the following error:
        "java.lang.UnsupportedOperationException: Layout pages with COSArray 
currently not supported."

I also tried this but nothing was happening.

        PDPageContentStream contentStream;
         PDDocument document = new PDDocument();
         PDPage page = new PDPage();
         document.addPage(page);
         AffineTransform transform;
for (PDDocument pdDocument : pdfDocList) {
            LayerUtility layerUtility = new LayerUtility(document);
            PDXObjectForm mountable = layerUtility.importPageAsForm(pdDocument, 
0);
            mountable.getPDStream().addCompression();
            contentStream = new PDPageContentStream(document, page);
            contentStream.appendRawCommands("q\n".getBytes("ISO-8859-1"));

            transform = new AffineTransform();
            transform.translate(18.0f, 18.0f);
            contentStream.drawXObject(mountable, transform);

            contentStream.appendRawCommands("Q\n".getBytes("ISO-8859-1"));
            contentStream.close();
        pdDocument.close();
}

Any help would be appreciated.


Thanks,
Lucy