return Lists.newArrayList(iterator()).toArray(array);
    }
  }

  private static final class FilteredKeyMap<K extends @Nullable Object, V extends @Nullable Object>
      extends AbstractFilteredMap<K, V> {
    final Predicate<? super K> keyPredicate;

    FilteredKeyMap(
        Map<K, V> unfiltered,
        Predicate<? super K> keyPredicate,
        Predicate<? super Entry<K, V>> entryPredicate) {

      return Lists.newArrayList(iterator()).toArray(array);
    }
  }

  private static final class FilteredKeyMap<K extends @Nullable Object, V extends @Nullable Object>
      extends AbstractFilteredMap<K, V> {
    final Predicate<? super K> keyPredicate;

    FilteredKeyMap(
        Map<K, V> unfiltered,
        Predicate<? super K> keyPredicate,
        Predicate<? super Entry<K, V>> entryPredicate) {