docx4j 8.2.9 is now in Maven Central.
The driver for this release is to ensure the namespace corresponding to the w16sdtdh is declared when docx4j manipulates a docx containing that prefix (which will be the case for documents edited in Word following recent updates).
http://schemas.microsoft.com/office/wor ... dtdatahash is new in [MS-DOCX] v15.0. Word (following recent updates) writes this namespace prefix to @mc:Ignorable in the MDP, for example, "w14 w15 w16se w16cid w16 w16cex w16sdtdh wp14". Since Word is unable to open a document if a prefix which appears in that attribute is not declared, the namespace must be declared.
Thanks to those who raised this issue.
To use docx4j 8.2.9 via Maven, just add one and only one of docx4j-JAXB-Internal, docx4j-JAXB-MOXy,
or docx4j-JAXB-ReferenceImpl to your pom. https://search.maven.org/search?q=g:org.docx4j
Otherwise, see https://www.docx4java.org/downloads.html
Minimum supported Java version is 8.0. (docx4j 11.2.9, a JPMS modularised release for Java 11 users will follow in coming days. Please note Java 11 users can use docx4j 8.2.9 if they wish)