I was able to solve this by attaching the sectPr of the last section to the document instead of a paragraph.

    SectPr sectPr = factory.createSectPr();
    SectPr.Type sectPrType = factory.createSectPrType();
    sectPrType.setVal("nextPage");

    sectPr.setType(sectPrType);

    wordprocessingMLPackage.getMainDocumentPart().getJaxbElement().getBody().setSectPr(sectPr);