*/
      return Collections.unmodifiableSet(delegate().get(key));
    }

    @Override
    public Set<Map.Entry<K, V>> entries() {
      return Maps.unmodifiableEntrySet(delegate().entries());
    }

    @Override
    public Set<V> removeAll(@Nullable Object key) {
      throw new UnsupportedOperationException();
    }

    @Override