List<Integer> result = []
        result.addAll(parentToChildClassIds.get(parentClassId))
        parentToChildClassIds.get(parentClassId).each {
            allVisibleChildClassIds(it, result)
        }
        return result
    }

    private allVisibleChildClassIds(int parentClassId, List<Integer> result) {
        def directChildrenIds = parentToChildClassIds.get(parentClassId)