public SortedMap<K, Collection<V>> subMap(
        @ParametricNullness K fromKey, @ParametricNullness K toKey) {
      return new SortedAsMap(sortedMap().subMap(fromKey, toKey));
    }

    @Override
    public SortedMap<K, Collection<V>> tailMap(@ParametricNullness K fromKey) {
      return new SortedAsMap(sortedMap().tailMap(fromKey));
    }

    @Nullable SortedSet<K> sortedKeySet;

    }

    @Override
    public SortedMap<K, V2> subMap(@ParametricNullness K fromKey, @ParametricNullness K toKey) {
      return transformEntries(fromMap().subMap(fromKey, toKey), transformer);
    }

    @Override
    public SortedMap<K, V2> tailMap(@ParametricNullness K fromKey) {
      return transformEntries(fromMap().tailMap(fromKey), transformer);
    }
  }

  @GwtIncompatible // NavigableMap

      standardClear();
    }

    @Override
    public boolean isEmpty() {
      return standardIsEmpty();
    }

    @Override
    public SortedMap<K, V> subMap(K fromKey, K toKey) {
      return standardSubMap(fromKey, toKey);
    }

    @Override
    public @Nullable Entry<K, V> lowerEntry(K key) {
      return standardLowerEntry(key);
    }

    @Override