for (Object key : keys) {
      remove(key);
    }
  }

  @LazyInit @RetainedWith @CheckForNull Set<K> keySet;

  @Override
  public Set<K> keySet() {
    // does not impact recency ordering
    Set<K> ks = keySet;
    return (ks != null) ? ks : (keySet = new KeySet());
  }

  @LazyInit @RetainedWith @CheckForNull Collection<V> values;

  @Override