private List<String> doubleAdd() {
        final List<String> stuff = new ArrayList<>();
        stuff.add("abc");
        stuff.add("abd");
        stuff.add("abe");
        stuff.add("abc");
        stuff.add("abd");
        stuff.add("abe");
        return stuff;
    }
Check ArraySet seems to work. :)

@author <a href="mailto:steinar@yahoo-inc.com">Steinar Knutsen</a>
vespajlib/src/test/java/com/yahoo/collections/ArraySetTestCase.java