class AddListAttributeModel {

    public void execute(String role, Request request, ModelBody modelBody) throws IOException {
        Deque<Object> composeStack = ComposeStackUtil.getComposeStack(request);
        ListAttribute listAttribute = new ListAttribute();
        listAttribute.setRole(role);
        composeStack.push(listAttribute);
        modelBody.evaluateWithoutWriting();
        listAttribute = (ListAttribute) composeStack.pop();
        ListAttribute parent = (ListAttribute) composeStack.peek();
        parent.add(listAttribute);
    }

}