* row and column iteration ordering of the returned table.
   *
   * @throws NullPointerException if {@code table} has a null key
   */
  @SuppressWarnings("unchecked") // TODO(cpovirk): Make constructor accept wildcard types?
  public static <R, C, V> ArrayTable<R, C, V> create(Table<R, C, ? extends @Nullable V> table) {
    return (table instanceof ArrayTable)
        ? new ArrayTable<R, C, V>((ArrayTable<R, C, V>) table)

   * row and column iteration ordering of the returned table.
   *
   * @throws NullPointerException if {@code table} has a null key
   */
  @SuppressWarnings("unchecked") // TODO(cpovirk): Make constructor accept wildcard types?
  public static <R, C, V> ArrayTable<R, C, V> create(Table<R, C, ? extends @Nullable V> table) {
    return (table instanceof ArrayTable)
        ? new ArrayTable<R, C, V>((ArrayTable<R, C, V>) table)

    assertThat(onlyPresent).containsExactly("a", "c").inOrder();
    assertThat(onlyPresent).containsExactly("a", "c").inOrder();
  }

  public void testPresentInstances_wildcards() {
    List<Optional<? extends Number>> optionals =
        ImmutableList.<Optional<? extends Number>>of(Optional.<Double>absent(), Optional.of(2));
    Iterable<Number> onlyPresent = Optional.presentInstances(optionals);

   * {@code lexicographical(Collections.reverseOrder(comparator))} (consider how each would order
   * {@code [1]} and {@code [1, 1]}).
   */
  // Note: 90% of the time we don't add type parameters or wildcards that serve only to "tweak" the
  // desired return type. However, *nested* generics introduce a special class of problems that we
  // think tip it over into being worthwhile.

  }

  public void testGetGenericSuperclass_wildcard_boundIsClass() {
    assertEquals(
        TypeToken.of(Object.class),
        TypeToken.of(Types.subtypeOf(Object.class)).getGenericSuperclass());
    assertEquals(
        new TypeToken<Object[]>() {},
        TypeToken.of(Types.subtypeOf(Object[].class)).getGenericSuperclass());
  }

  public void testGetGenericSuperclass_wildcard_boundIsInterface() {

     * Iterable<? extends S>}. However, the need for this comes up so rarely
     * that it doesn't justify making everyone else deal with the very ugly
     * wildcard.
     */
    return new LexicographicalOrdering<S>(this);
  }

  // Regular instance methods

  @Override
  public abstract int compare(@ParametricNullness T left, @ParametricNullness T right);

    assertThat(onlyPresent).containsExactly("a", "c").inOrder();
    assertThat(onlyPresent).containsExactly("a", "c").inOrder();
  }

  public void testPresentInstances_wildcards() {
    List<Optional<? extends Number>> optionals =
        ImmutableList.<Optional<? extends Number>>of(Optional.<Double>absent(), Optional.of(2));
    Iterable<Number> onlyPresent = Optional.presentInstances(optionals);

    numberKeyed = transformEntries(map6, transformer);
    integerKeyed = transformEntries(map8, transformer);
    integerKeyed = transformEntries(map9, transformer);

    Map<? extends Number, Double> wildcarded = transformEntries(map0, transformer);

    // Can't loosen the key type:
    // objectKeyed = transformEntries(map5, transformer);
    // objectKeyed = transformEntries(map6, transformer);

    numberKeyed = transformEntries(map6, transformer);
    integerKeyed = transformEntries(map8, transformer);
    integerKeyed = transformEntries(map9, transformer);

    Map<? extends Number, Double> wildcarded = transformEntries(map0, transformer);

    // Can't loosen the key type:
    // objectKeyed = transformEntries(map5, transformer);
    // objectKeyed = transformEntries(map6, transformer);

    // Ideally, the returned equivalence would support Iterable<? extends T>. However,
    // the need for this is so rare that it's not worth making callers deal with the ugly wildcard.
    return new PairwiseEquivalence<>(this);
  }

  /**
   * Returns a predicate that evaluates to true if and only if the input is equivalent to {@code
   * target} according to this equivalence relation.