@Override
    public @Nullable K higherKey(@ParametricNullness K key) {
      return fromMap().higherKey(key);
    }

    @Override
    public @Nullable Entry<K, V2> lastEntry() {
      return transformEntry(fromMap().lastEntry());
    }

    @Override
    public @Nullable Entry<K, V2> lowerEntry(@ParametricNullness K key) {
      return transformEntry(fromMap().lowerEntry(key));
    }

    @Override
    public @Nullable K higherKey(@ParametricNullness K key) {
      return fromMap().higherKey(key);
    }

    @Override
    public @Nullable Entry<K, V2> lastEntry() {
      return transformEntry(fromMap().lastEntry());
    }

    @Override
    public @Nullable Entry<K, V2> lowerEntry(@ParametricNullness K key) {
      return transformEntry(fromMap().lowerEntry(key));
    }