Hi Jason,
We managed successfully to integrate the docx4j library into some projects here, however there is something we would like to use that apparently is not supported.
There is an issue with Simple Fields (w:fldSimple).
Due to security reasons, I can't give you the full Word document, but I can give you the related xml sources :
header2_output.xml
header2_input.xml
In the prepared template with OpenDoPE ...