docx4j 11.5.1 and 8.3.1 are now available in Maven Central. For downloads, go to https://www.docx4java.org/downloads.html
w16sdtfl has started to show up in Word releases, despite not yet being specified in . So the immediate driver for these releases is to ensure the namespace corresponding to the w16sdtfl is declared when docx4j manipulates a docx containing that prefix (which will be the case for documents edited in Word after the ...