I generate PMD reports through the "mvn clean install site" command. This generates PMD report files correctly within the Maven site. But the PMD jenkins plugin doesn't seem to pick them up at all. In the build status I see:

PMD: 0 warnings from 0 PMD files

Plus I know from the Maven site reports that there are some PMD warnings.

My Maven project 4 modules. The parent pom configures the PMD plugin, but since it has no code, it contains no pmd.xml

If I look at the Jenkins workspace, I can find the pmd.xml correctly in <module>/target/pmd.xml, for each module.