Torsten Kleiber has released a new version of the PMD JDeveloper plugin! The first release in two years, this brings the plugin up to date so that it now includes PMD 4.0 - and it also works with JDeveloper 11. You can get the plugin here:
https://sourceforge.net/project/showfiles.php?group_id=56262&package_id=75287&release_id=530073
Thanks to Torsten for getting this plugin up to date!