void () { List<Integer> l = ContainerUtil.concat(Arrays.asList(1, 2), Collections.emptyList(), Arrays.asList(3, 4)); assertEquals(4, l.size()); assertEquals(1, (int)l.get(0)); assertEquals(2, (int)l.get(1)); assertEquals(3, (int)l.get(2)); assertEquals(4, (int)l.get(3)); try { l.get(-1); fail(); } catch (IndexOutOfBoundsException ignore) { } try { l.get(4); fail(); } catch (IndexOutOfBoundsException ignore) { } }