XOM 1.2.10 is not compatible with JDK 16 as it has classes that subclass internal JDK classes. JDK 16 will reject this unless appropriate -add-exports are added, which we don't want to do.

As noted in it's release notes, xom 1.3.7 has corrected this.

https://github.com/elharo/xom/releases/tag/v1.3.7