"multiset doesn't contains element after retaining its entry",
        getMultiset().contains(e0()));
  }

  @CollectionSize.Require(ONE)
  @CollectionFeature.Require(SUPPORTS_REMOVE)
  public void testEntrySet_retainAllAbsent() {
    assertTrue(
        "multiset.entrySet.retainAll(missingEntry) returned true",
        getMultiset().entrySet().retainAll(singleton(Multisets.immutableEntry(e0(), 2))));
    assertFalse(