For classes with companion objects, Kotlin compiler generates a 'Companion' static accessor field.
Java prioritizes fields over inner types (apparently, Scala does this as well, KT-29864), so the generated initializer doesn't compile.
As a workaround, initializer generatation is disabled for enum fields inside companion objects. Certainly, it's not a proper fix, however it does fix the regression.
Yan Zhulanow
a44fd964cf