guava/src/com/google/common/collect/StandardRowSortedTable.java
@Override
  public SortedMap<R, Map<C, V>> rowMap() {
    return (SortedMap<R, Map<C, V>>) super.rowMap();
  }
@Override
  public SortedMap<R, Map<C, V>> rowMap() {
    return (SortedMap<R, Map<C, V>>) super.rowMap();
  }
{@inheritDoc}

<p>This method returns a {@link SortedMap}, instead of the {@code Map} specified in the {@link
Table} interface.