Ok guys, I found it on my own.
I injected util class inside singleton LawCaseManager, which was injected during app creation. I searched for some injection cycles/endless loops or race conditions, but haven't found any obvious one.
All in all, when I removed injection inside singleton class, everything worked like always. I searched over my older projects and it appears, that I used singletons only for data managers, which were holding app state and none of them had injection of any other class. I am curious, if it was only specific case or is it some grand rule, that guice forbids injection inside singleton class? :O