*/
  public static <K extends @Nullable Object, V extends @Nullable Object>
      SortedSetMultimap<K, V> unmodifiableSortedSetMultimap(SortedSetMultimap<K, V> delegate) {
    if (delegate instanceof UnmodifiableSortedSetMultimap) {
      return delegate;
    }
    return new UnmodifiableSortedSetMultimap<>(delegate);
  }

  /**

   */
  public static <K extends @Nullable Object, V extends @Nullable Object>
      SortedSetMultimap<K, V> unmodifiableSortedSetMultimap(SortedSetMultimap<K, V> delegate) {
    if (delegate instanceof UnmodifiableSortedSetMultimap) {
      return delegate;
    }
    return new UnmodifiableSortedSetMultimap<>(delegate);
  }

  /**

    tree.put(1.0, 2.0);
    tree.put(2.0, 3.0);
    tree.put(3.0, 4.0);
    tree.put(4.0, 5.0);

    SortedSetMultimap<Double, Double> sorted = Multimaps.unmodifiableSortedSetMultimap(tree);
    TreeMultimap<Double, Double> copyFromSorted = TreeMultimap.create(sorted);
    assertEquals(tree, copyFromSorted);
    assertSame(Ordering.natural(), copyFromSorted.keyComparator());