JeremiasMaerki provides a plug-in for Apache FOP that allows to use a PDF file in an fo:external-graphic element. The plug-in is published under the same license as Apache FOP, i.e. the Apache License v2.0.
Requirements:
For the plug-in to work you need FOP Trunk (from the Subversion repository) with revision 588547 or later.
The plug-in itself (download link above)
Please note that this functionality doesn't work with FOP 0.94 or earlier! The functionality is somewhat experimental.
For instructions on how to enabled this functionality, please read the README file in the distribution package!
FAQ
Why is this not integrated with Apache FOP?
Because the plug-in uses
PDFBox and that would introduce a new dependency on FOP. We may integrate this functionality directly into FOP one day.