assertFalse("removeIf(x -> false) should return false", collection.removeIf(x -> false));
    expectUnchanged();
  }

  @CollectionFeature.Require(SUPPORTS_ITERATOR_REMOVE)
  @CollectionSize.Require(absent = ZERO)
  public void testRemoveIf_sometimesTrue() {
    assertTrue(
        "removeIf(isEqual(present)) should return true",
        collection.removeIf(Predicate.isEqual(samples.e0())));

    assertFalse("removeIf(x -> false) should return false", collection.removeIf(x -> false));
    expectUnchanged();
  }

  @CollectionFeature.Require(SUPPORTS_ITERATOR_REMOVE)
  @CollectionSize.Require(absent = ZERO)
  public void testRemoveIf_sometimesTrue() {
    assertTrue(
        "removeIf(isEqual(present)) should return true",
        collection.removeIf(Predicate.isEqual(samples.e0())));

    return false;
  }

  @Override
  public boolean removeAll(Collection<?> c) {
    return Iterables.removeIf(
        multimap.unfiltered().entries(),
        and(multimap.entryPredicate(), valuePredicateOnEntries(in(c))));
  }

  @Override
  public boolean retainAll(Collection<?> c) {
    return Iterables.removeIf(
        multimap.unfiltered().entries(),

  }

  @Override
  public final boolean removeAll(Collection<?> oldElements) {
    throw new UnsupportedOperationException();
  }

  @Override
  public final boolean removeIf(Predicate<? super E> predicate) {
    throw new UnsupportedOperationException();
  }

  @Override
  public final boolean retainAll(Collection<?> elementsToKeep) {
    throw new UnsupportedOperationException();
  }