Major Description
On the CI server, some unit tests are failing for maven-pmd-plugin (https://builds.apache.org/job/maven-plugins/).
It seems that the tests run fine on the slave "ubuntu2" but not on "ubuntu3".
ubuntu2 workspace path:
/home/hudson/hudson-slave/workspace/maven-plugins
ubuntu3 workspace path:
/home/jenkins/jenkins-slave/workspace/maven-plugins
However, PMD found violations in the following file:
/x1/jenkins/jenkins-slave/workspace/maven-plugins/maven-pmd-plugin/src/test/resources/unit/default-configuration/def/configuration/App.java
This could indicate the /x1 is actually a sym-link to /home. Maven-pmd-plugin sees /home/... and PMD sees /x1/.... PMD reports violations against /x1 but the maven-pmd-plugin doesn't know about this (it requested to process files under /home) - so the internal PmdFileInfo object couldn't not be determined.
Assuming the above is correct, then the attached patch could solve this problem. It determines the canonical paths of the files to be processed, hoping that the filenames are unique then. However, I could not reproduce this problem locally (I started maven from commandline instead letting Jenkins start it, maybe that's the difference?).