[MPMD-191] Update to PMD 5.2.1

Changes in PMD:
* http://pmd.sourceforge.net/pmd-5.2.1/overview/changelog.html
* http://pmd.sourceforge.net/pmd-5.2.0/overview/changelog.html
* http://pmd.sourceforge.net/pmd-5.1.3/changelog.html