protected void mergeContributor_Roles(
            Contributor target, Contributor source, boolean sourceDominant, Map<Object, Object> context) {
        List<String> src = source.getRoles();
        if (!src.isEmpty()) {
            List<String> tgt = target.getRoles();
            List<String> merged = new ArrayList<>(tgt.size() + src.size());
            merged.addAll(tgt);
            merged.addAll(src);