}
  }

  @Override
  ImmutableSet<K> createKeySet() {
    @SuppressWarnings("unchecked")
    ImmutableList<K> keyList =
        (ImmutableList<K>) new KeysOrValuesAsList(alternatingKeysAndValues, 0, size);
    return new KeySet<K>(this, keyList);
  }

  static final class KeysOrValuesAsList extends ImmutableList<Object> {
    private final transient @Nullable Object[] alternatingKeysAndValues;