@Override
        public void addDataListener(Runnable listener) {
            throw new IllegalStateException("We're not supposed to listen to or add to this");
        }
This must be pushed on the stack first to get things started off, given that the stack is expected to
contain the parent of each element (including the topmost)
container-core/src/main/java/com/yahoo/processing/rendering/AsynchronousSectionedRenderer.java