Opening a test result with a empty className tag in junitReport.xml file results in a 404 page. For those, generated URL to open the test result page is lacking className. URL looks like this: http://JENKINS/job/junit/1/testReport/junit/(root)//testName/

There's just '//' in place of /className/ in the URL. This causes PackageResult.getDynamic() to fail to lookup the TestResult.