As we discussed via email,
In latest nightly build, FlashPaper to PDF conversion is available via commandline.
Here is part of your last email:
I've tried to run your nightly build but it take very long time (ok, not very a problem)
and crash after 56 pages with a OOME (OutOfMemoryError).
I've increased the memory allocated to the process but for large document (ex 128 pages)
it stop with OOME also.
For iText, it exist a LGPL fork available here: https://github.com/ymasory/iText-4.2.0
An alternative will be also to export document to ODT (LibreOffice Writer).
Actually, only the test with a Zoom factor 5 is working for small documents (52 pages).
But it's again a nightly build, so an alpha version and it will surely be optimized.