}
        }

        @Override
        protected Activation.Builder transformActivation_Os(
                Supplier<? extends Activation.Builder> creator, Activation.Builder builder, Activation target) {
            stk.push(nextFrame("os", Activation::getOs));
            try {
                return super.transformActivation_Os(creator, builder, target);
            } finally {
                stk.pop();
            }