Using xUnit in a Pipeline in a step :

step([$class: 'XUnitBuilder', thresholds: [[$class: 'FailedThreshold', unstableThreshold: '0']], tools: [ [$class: 'PHPUnitJunitHudsonTestType', pattern: 'tests/_log/report.xml'], [$class: 'JUnitType', pattern: 'web/junit.xml']]])

After updating from xUnit 2.3 to 2.3.1, I face the following exception :
java.lang.NoClassDefFoundError: Could not initialize class com.sun.org.apache.xerces.internal.impl.dv.xs.SchemaDVFactoryImpl
The full stack trace is attached.

Downgrading to xUnit 2.3 seems to solve the problem.

There seem to be only one related commit between the two xUnit releases.