}

  public void testSetCount_0_nonePresent() {
    when(backingMap.get(KEY)).thenReturn(null);

    assertEquals(0, multiset.setCount(KEY, 0));
  }

  public void testSerialCycle() {
    ConcurrentHashMultiset<ContainsMultiset> multiset = ConcurrentHashMultiset.create();
    ContainsMultiset containsMultiset = new ContainsMultiset(multiset);
    multiset.add(containsMultiset);