private TreeSet<Choice> getAlphabeticallySortedContent() {
        if (alphaSortedContent == null) {
            flatContent(); // ensure we have the positions on the Choices
            alphaSortedContent = new TreeSet<>(new ChoiceTextComparator(strComparator));
            alphaSortedContent.addAll(content);
        }

        return alphaSortedContent;
    }
private TreeSet<Choice> getAlphabeticallySortedContent()