assertTrue(dest.contains("new2"));
        // Should not have duplicate "existing"
        assertEquals(1, dest.stream().filter(s -> s.equals("existing")).count());
    }

    @Test
    public void testConcatKinds() {
        // Test static concatKinds method
        SuggestItem.Kind[] kinds1 = { SuggestItem.Kind.QUERY };
        SuggestItem.Kind[] kinds2 = { SuggestItem.Kind.DOCUMENT, SuggestItem.Kind.QUERY };