@NonNull
    public Set<Integer> getCheckedButtonIndexes() {
        final Set<Integer> checkedButtonIndexes = new HashSet<>();
        int idx = 0;
        for (CompoundButton child : this.valueButtons) {
            if (child.isChecked()) {
                checkedButtonIndexes.add(idx);
            }
            idx++;
        }

        return checkedButtonIndexes;
    }
adds chips to this group programatically
main/src/main/java/cgeo/geocaching/ui/ChipChoiceGroup.java