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 Iterables.removeIf(
        multimap.unfiltered().entries(),
        // explicit <Entry<K, V>> is required to build with JDK6
        Predicates.<Entry<K, V>>and(
            multimap.entryPredicate(), Maps.<V>valuePredicateOnEntries(Predicates.in(c))));
  }

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

        // Find accessors that were not removed but should be
        Map<AccessorKey, ReplacedAccessor> keptAccessors = new HashMap<>(oldAccessorsOfUpgradedProperties);
        keptAccessors.entrySet().removeIf(e -> {
            if (seenUpgradedAccessorsChanges.contains(e.getKey())) {
                return true;
            }
            ReplacedAccessor accessor = e.getValue();

    return Iterables.removeIf(
        multimap.unfiltered().entries(),
        // explicit <Entry<K, V>> is required to build with JDK6
        Predicates.<Entry<K, V>>and(
            multimap.entryPredicate(), Maps.<V>valuePredicateOnEntries(Predicates.in(c))));
  }

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

    throw new UnsupportedOperationException();
  }

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

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

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