detect the plugin responsible for run configuration AbstractMethodError (IDEA-119173)
 CR-IU-494 EmptyActionGroup extracted. Both EmptyXXX classes made final, javadoc improved.
CR-IC-3880 (test added)
prevent cancellation upon removing data from indices, to avoid state data in e.g. stub index IDEA-117290
IDEA-119151 Unable use 'Revert' in Editor Panel