* Table} interface.
   */
  @Override
  public SortedMap<R, Map<C, V>> rowMap() {
    return (SortedMap<R, Map<C, V>>) super.rowMap();
  }

  @Override
  SortedMap<R, Map<C, V>> createRowMap() {
    return new RowSortedMap();
  }

  @WeakOuter
  private class RowSortedMap extends RowMap implements SortedMap<R, Map<C, V>> {
    @Override
    public SortedSet<R> keySet() {

  @Override
  public Map<R, Map<C, V>> rowMap() {
    Map<R, Map<C, V>> result = rowMap;
    return (result == null) ? rowMap = createRowMap() : result;
  }

  Map<R, Map<C, V>> createRowMap() {
    return new RowMap();
  }

  @WeakOuter
  class RowMap extends ViewCachingAbstractMap<R, Map<C, V>> {
    @Override