This library is historically used by the Apache Maven project so it's developed and maintained by the same bad guys

The current master is now at https://github.com/codehaus-plexus/plexus-utils

For publishing the site do the following:

mvn -Preporting verify site site:stage scm-publish:publish-scm

Starting with version 4, XML classes (in org.codehaus.plexus.util.xml and org.codehaus.plexus.util.xml.pull) have been extracted to a separate plexus-xml 4: if you need them, just use this new artifact.