I build a java project to test directly without soapui. No problem !
I decide to test directly the code, without eclipse. So with a single .bat, I can test the java code and manage the classpath.
So, according the order of inclusion of the two xmlbeans generated jar, the code runs without problem or has the same cast bug.
As the linux and windows class loader are differents, the order of inclusion of the two xmlbeans generated jar are not the same. So there is bug or not bug.
Now, I have to understand how to manage the inclusion order in soapui-Pro.
I have just tested by putting a .jar into the lib folder (so it is first loaded) and the second one is in bin/ext folder (so it is loaded later) : No bug,