Currently the Clover reports mix production and test code. This is due to a misunderstanding (by bad documentation). The testsources in clover-setup are treated different than at reporting time. In clover setup they are only used to figure out where tests could possibly be, but final decision is done on the file name and annotations. All code inside testsources of cloversetup thats not a real test is treated as application class. So we see our test-framework classes and utility classes between our production code in the report.
To fix this, the clover-report task must get a fileset (unfortunately, with same name like clover-setup to make it more confusing) that selects all java files which are part of test code (testcases and utility code).
Once I figured this out this was easy to fix!