It looks like that the pmd-eclipse plugin doesn't execute the start()/end() methods on Rule, RuleSet or RuleSets.
This is inconsistent behavior, e.g. PMD itself and the maven pmd plugin both execute these methods once.
Either PMD should provide a better interface for the eclipse plugin or the eclipse plugin should simply call start() manually.
Issues: #1506
Discussion: Sonar PMD Plugin seem doesn't invoke start(RuleContext ctx) and end(RuleContext ctx)
This will be fixed with the next version.
You can test the new version by installing the latest plugin version from
https://sourceforge.net/projects/pmd/files/pmd-eclipse/update-site-latest/