The property 'javax.xml.transform.TransformerFactory' is not defined by default at the JVM level. The property exists to allow the user to set the transformer factory as he wants.
I think the best solution for now is to set the property to the Sun default transformer factory in the launcher as we officially support Sun JVM. If an user wants to use another JVM even if we do not support it for now, he can change the property in the launcher.
Later the launcher must evolute if we want support other JVM.
Caution, Xalan 2.7.0 contains a bug about Transformer.reset() that is needed to improve performances and memory consumption reusing transformers:
https://issues.apache.org/jira/browse/XALANJ-2395