There are some kind of pdfs like the one in resources folder (scansmpl.pdf), that I can't add a text on it. I think that they are scanned PDFs.
If you run main class, it generates a pdf named wwii.pdf in resources folder. If you open it, you can't see the text added by main class to original pdf. Actually, when I use appendMode.PREPEND, on mouse over, I can see that the text is there, maybe, behind the pdf. When I use AppendMode.APPEND, I can't even find the text.