* user-defined properties.
 *
 * <p>A {@code Graph} built by this class has the following default properties:
 *
 * <ul>
 *   <li>does not allow self-loops
 *   <li>orders {@link Graph#nodes()} in the order in which the elements were added (insertion
 *       order)
 * </ul>
 *
 * <p>{@code Graph}s built by this class also guarantee that each collection-returning accessor
 * returns a <b>(live) unmodifiable view</b>; see <a

          @Override
          protected Iterator<Integer> newTargetIterator() {
            return ImmutableList.of(1, 2).iterator();
          }
        };
    assertFailure(tester);
  }

  public void testUnknownOrder() {
    new IteratorTester<Integer>(
        3, MODIFIABLE, newArrayList(1, 2), IteratorTester.KnownOrder.UNKNOWN_ORDER) {
      @Override

              }
            })
        .named("checkedNavigableSet/TreeSet, natural")
        .withFeatures(
            SetFeature.GENERAL_PURPOSE,
            CollectionFeature.KNOWN_ORDER,
            CollectionFeature.SERIALIZABLE,
            CollectionFeature.FAILS_FAST_ON_CONCURRENT_MODIFICATION,
            CollectionFeature.RESTRICTS_ELEMENTS,
            CollectionSize.ANY)

    @Override
    public Iterable<Entry<E>> order(List<Entry<E>> insertionOrder) {
      // We mimic the order from gen.
      Map<E, Entry<E>> map = new LinkedHashMap<>();
      for (Entry<E> entry : insertionOrder) {
        map.put(entry.getElement(), entry);
      }

      Set<E> seen = new HashSet<>();
      List<Entry<E>> order = new ArrayList<>();
      for (E e : gen.order(new ArrayList<E>(map.keySet()))) {

        .withFeatures(
            CollectionFeature.GENERAL_PURPOSE, CollectionFeature.KNOWN_ORDER, CollectionSize.ANY)
        .suppressing(suppressForLinkedBlockingQueue())
        .createTestSuite();
  }

  // Not specifying KNOWN_ORDER for PriorityQueue and PriorityBlockingQueue
  // even though they do have it, because our tests interpret KNOWN_ORDER to
  // also mean that the iterator returns the head element first, which those
  // don't.

  }

  /**
   * Returns an immutable list containing the given elements, in order.
   *
   * @throws NullPointerException if any element is null
   */
  public static <E> ImmutableList<E> of(E e1, E e2) {
    return construct(e1, e2);
  }

  /**
   * Returns an immutable list containing the given elements, in order.
   *
   * @throws NullPointerException if any element is null
   */

   * com.google.common.collect.testing.features.CollectionFeature#KNOWN_ORDER}, the tests will look
   * only at the returned contents without regard for order.
   */
  Iterable<E> order(List<E> insertionOrder);

   * com.google.common.collect.testing.features.CollectionFeature#KNOWN_ORDER}, the tests will look
   * only at the returned contents without regard for order.
   */
  Iterable<E> order(List<E> insertionOrder);

        .withFeatures(
            CollectionFeature.GENERAL_PURPOSE, CollectionFeature.KNOWN_ORDER, CollectionSize.ANY)
        .suppressing(suppressForLinkedBlockingQueue())
        .createTestSuite();
  }

  // Not specifying KNOWN_ORDER for PriorityQueue and PriorityBlockingQueue
  // even though they do have it, because our tests interpret KNOWN_ORDER to
  // also mean that the iterator returns the head element first, which those
  // don't.

 * @since 2.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public abstract class Ordering<T extends @Nullable Object> implements Comparator<T> {
  // Natural order

  /**
   * Returns a serializable ordering that uses the natural order of the values. The ordering throws
   * a {@link NullPointerException} when passed a null parameter.
   *