org.dom4j.DocumentFactory.getInstance throws

Apparently a fix that is in the createSingleton(String name) class is not applied in createSingleton(). It causes the getInstance to throw "java.lang.ClassCastException: org.dom4j.DocumentFactory cannot be cast to org.dom4j.DocumentFactory" whenever there is class loader mismatch.

There is couple of bug reports filed that report similar behaviour I was experiencing:
[JENKINS-15344](https://issues.jenkins-ci.org/browse/JENKINS-15344) 
[JENKINS-13709](https://issues.jenkins-ci.org/browse/JENKINS-13709)
[JENKINS-7666](https://issues.jenkins-ci.org/browse/JENKINS-7666) 
[JENKINS-17488](https://issues.jenkins-ci.org/browse/JENKINS-17488)