Yetus flagging two badly formatted xml files. Seemingly related are the two filenotfoundexceptions that show in the xml.txt build product. https://builds.apache.org/view/H-L/view/HBase/job/HBase%20Nightly/job/branch-2.0/1399/artifact/output-general/xml.txt
The complaint is that the xml dtds are not found.
Indeed they were moved long time ago: https://github.com/checkstyle/checkstyle/issues/1571
They were supposed to stick around at their old location but that seems to have changed recently.