* @throws NullPointerException if any of {@code elements} is null
   */
  public static <E> ImmutableSortedMultiset<E> copyOf(Iterable<? extends E> elements) {
    // Hack around E not being a subtype of Comparable.
    // Unsafe, see ImmutableSortedMultisetFauxverideShim.
    @SuppressWarnings("unchecked")
    Ordering<E> naturalOrder = (Ordering<E>) Ordering.<Comparable<?>>natural();

     * helps to shortcut most calls to isEmpty(), which is important because the check for emptiness
     * is relatively expensive. Use a subtype so this also doesn't need any extra storage.
     */
    private static final class UnconditionalValueHolder extends ValueHolder {}
  }

  private MoreObjects() {}

          // subtyping between declared type bound and actual type bound. So it's possible that we
          // may generate something like <capture#1-of ? extends Foo&SubFoo>.
          // Checking subtype between declared and actual type bounds
          // adds recursive isSubtypeOf() call and feels complicated.
          // There is no contract one way or another as long as isSubtypeOf() works as expected.

   * restrictive. However, the ideal signature, {@code public <S super T> S or(S)}, is not legal
   * Java. As a result, some sensible operations involving subtypes are compile errors:
   *
   * {@snippet :
   * Optional<Integer> optionalInt = getSomeOptionalInt();
   * Number value = optionalInt.or(0.5); // error
   *

   * @throws NullPointerException if any of {@code elements} is null
   */
  public static <E> ImmutableSortedMultiset<E> copyOf(Iterable<? extends E> elements) {
    // Hack around E not being a subtype of Comparable.
    // Unsafe, see ImmutableSortedMultisetFauxverideShim.
    @SuppressWarnings("unchecked")
    Ordering<E> naturalOrder = (Ordering<E>) Ordering.<Comparable<?>>natural();

    setImplementation(ThreadFactory.class, Dummies.DummyThreadFactory.class);
    setImplementation(Executor.class, Dummies.DummyExecutor.class);
  }

  @SuppressWarnings("unchecked") // it's a subtype map
  private static <T> @Nullable Class<? extends T> getImplementation(Class<T> type) {
    return (Class<? extends T>) implementations.get(type);
  }

    setImplementation(ThreadFactory.class, Dummies.DummyThreadFactory.class);
    setImplementation(Executor.class, Dummies.DummyExecutor.class);
  }

  @SuppressWarnings("unchecked") // it's a subtype map
  private static <T> @Nullable Class<? extends T> getImplementation(Class<T> type) {
    return (Class<? extends T>) implementations.get(type);
  }

 * GraphBuilder} class:
 *
 * {@snippet :
 * MutableGraph<Integer> graph = GraphBuilder.undirected().build();
 * }
 *
 * <p>{@link GraphBuilder#build()} returns an instance of {@link MutableGraph}, which is a subtype
 * of {@code Graph} that provides methods for adding and removing nodes and edges. If you do not
 * need to mutate a graph (e.g. if you write a method than runs a read-only algorithm on the graph),

 * GraphBuilder} class:
 *
 * {@snippet :
 * MutableGraph<Integer> graph = GraphBuilder.undirected().build();
 * }
 *
 * <p>{@link GraphBuilder#build()} returns an instance of {@link MutableGraph}, which is a subtype
 * of {@code Graph} that provides methods for adding and removing nodes and edges. If you do not
 * need to mutate a graph (e.g. if you write a method than runs a read-only algorithm on the graph),

          // subtyping between declared type bound and actual type bound. So it's possible that we
          // may generate something like <capture#1-of ? extends Foo&SubFoo>.
          // Checking subtype between declared and actual type bounds
          // adds recursive isSubtypeOf() call and feels complicated.
          // There is no contract one way or another as long as isSubtypeOf() works as expected.