Ok I finally found the problem : when I build by hand, there is a soapui-settings.xml file in my home directory that is picked-up and it enables some feature I'm currently working on. The unit tests are working with my feature enabled.
When I built through jenkins, no soapui-settings.xml was present and thus my changes were not enabled and the unit tests did fail.
So the unit tests are doing their job pretty well : my changes are causing the failures. And the problem is not directly related to the version of java, the version of maven or the fact that it is executed through a jenkins job.
Sorry for the noise.
(This makes me wonder if the maven build should be configured to explicitly use a "blessed" soapui-settings.xml file when running tests ?)
