private static class ActivationWalker extends MavenTransformer {

        private final Deque<ActivationFrame> stk;

        ActivationWalker(Deque<ActivationFrame> stk, UnaryOperator<String> transformer) {
            super(transformer);
            this.stk = stk;
        }

        private ActivationFrame nextFrame(String property) {
            return new ActivationFrame(property, Optional.empty());
        }