* exposes as many getters, does work in the constructor, and has both a superclass and a subclass
   */
  public static class SortedMapSubmapTestMapGenerator<
          K extends @Nullable Object, V extends @Nullable Object>
      extends ForwardingTestMapGenerator<K, V> implements TestSortedMapGenerator<K, V> {
    final Bound to;
    final Bound from;