Dwc-A related tests can failed on Travis CI

[cgendreau]

testDwcAFileGenerationSynonym and testDwcAFileGenerationAccepted sometimes failed on Travis CI. You can see that tests are working on 2/3 of the JDK. Simply relaunching the test alone will work.

I was never able to reproduce the issue locally. The hint I have is: the HTTP session might be part of the issue since the 'filename' is stored in the session so if a test ends up with the wrong file name the test will fail.