QR Code from Primefaces (JSF) page?

Hi all,

I have a question - maybe it´s completely wrong what I try to do:
I have a XHTML page which includes a barcode from Primefaces:
http://primefaces.org/showcase/ui/multimedia/barcode.xhtml?jfwid=d6c40

Should this code appearing for the current Open HTML to PDF implementation?
Currently I have an issue with the session, Primefaces is saying that I have no valid session....

If change it to:, I got no exception, but the QR Code is also not showing...
`builder.withW3cDocument(doc, null);`

I saw also this post here:
https://github.com/danfickle/openhtmltopdf/wiki/Plugins:-1D-2D-Barcode-with-ZXing

But here seems like also "ZXingObjectDrawer" is not valid?

Can anybody help me?