private static @Nullable String getTopmostOwnerClassQualifiedName(@NotNull PsiClass psiClass) {
      PsiClass ownerClass = null;
      for (PsiClass aClass = psiClass.getContainingClass(); aClass != null; aClass = aClass.getContainingClass()) {
        ownerClass = aClass;
      }
      if (ownerClass != null) {
        return ownerClass.getQualifiedName();
      }
      return null;
    }
private static @Nullable String getTopmostOwnerClassQualifiedName(@NotNull PsiClass psiClass)