An error in junit test kotlin

Hi @tasso94
Thanks for guiding .

I added companion object {
in top of the @ClassRule annotation and now i faced by this error :

The @ClassRule 'rule' must be public.

Actually i think var rule = TestCoverageProcessEngineRuleBuilder.create().build()
Is public and static in kotlin .
I think problem is related to rule .
Because in this topic :

mentioned if we use Spring boot , we shouldn’t use ProcessEngineRule .
Is that true or i got wrong meaning ?