@Test
    public void testContainsAll() {
        final String string = "abc";
        final String a = new String(string);
        final String b = new String(string);
        final String c = "c";
        final List<String> stuff = new ArrayList<>();
        stuff.add(string);
        stuff.add(a);
        stuff.add(b);
        final ArraySet<String> t = new ArraySet<>(
                stuff.size());
        t.addAll(stuff);
        assertTrue(t.containsAll(stuff));
        stuff.add(c);
        assertFalse(t.containsAll(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