@Test
public void testPollNMulti() {

  LOG.info("Test pollN multi");
  // use addAll
  set.addAll(list);
  // poll existing elements
  List<Integer> l = set.pollN(10);
  assertEquals(10, l.size());
  for (int i = 0; i < 10; i++) {
    assertEquals(list.get(i), l.get(i));
  }
  // poll more elements than present
  l = set.pollN(1000);
  assertEquals(NUM - 10, l.size());
  // check the order
  for (int i = 10; i < NUM; i++) {
    assertEquals(list.get(i), l.get(i - 10));
  }
  // set is empty
  assertTrue(set.isEmpty());
  assertEquals(0, set.size());
  LOG.info("Test pollN multi - DONE");
}