@CollectionSize.Require(absent = ZERO)
  public void testIsEmptyNo() {
    assertFalse(multimap().isEmpty());
  }

  @CollectionSize.Require(absent = ZERO)
  @MapFeature.Require(ALLOWS_NULL_KEYS)
  public void testSizeNullKey() {
    initMultimapWithNullKey();
    assertEquals(getNumElements(), multimap().size());
    assertFalse(multimap().isEmpty());
  }

  @CollectionSize.Require(absent = ZERO)