}
  }

  @GwtIncompatible // NavigableMap
  private static class TransformedEntriesNavigableMap<
          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
      extends TransformedEntriesSortedMap<K, V1, V2> implements NavigableMap<K, V2> {

    TransformedEntriesNavigableMap(
        NavigableMap<K, V1> fromMap, EntryTransformer<? super K, ? super V1, V2> transformer) {

    }
  }

  @GwtIncompatible // NavigableMap
  private static class TransformedEntriesNavigableMap<
          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
      extends TransformedEntriesSortedMap<K, V1, V2> implements NavigableMap<K, V2> {

    TransformedEntriesNavigableMap(
        NavigableMap<K, V1> fromMap, EntryTransformer<? super K, ? super V1, V2> transformer) {