*
   * <p>If the graph is directed, the resultant edge will be directed; otherwise, it will be
   * undirected.
   *
   * <p>If this graph is directed, {@code endpoints} must be ordered.
   *
   * <p>Values do not have to be unique. However, values must be non-null.
   *
   * <p>If either or both endpoints are not already present in this graph, this method will silently

  public void testForEachKnownOrder() {
    List<E> elements = new ArrayList<>();
    collection.forEach(elements::add);
    List<E> expected = copyToList(getOrderedElements());
    assertEquals("Different ordered iteration", expected, elements);
  }

    Helpers.testComparator(comparator, ordered);
    assertThat(SerializableTester.reserialize(comparator)).isSameInstanceAs(comparator);

    // The Java implementation.
    Comparator<byte[]> javaImpl = UnsignedBytes.lexicographicalComparatorJavaImpl();
    Helpers.testComparator(javaImpl, ordered);
    assertThat(SerializableTester.reserialize(javaImpl)).isSameInstanceAs(javaImpl);
  }

    Helpers.testComparator(comparator, ordered);
    assertThat(SerializableTester.reserialize(comparator)).isSameInstanceAs(comparator);

    // The Java implementation.
    Comparator<byte[]> javaImpl = UnsignedBytes.lexicographicalComparatorJavaImpl();
    Helpers.testComparator(javaImpl, ordered);
    assertThat(SerializableTester.reserialize(javaImpl)).isSameInstanceAs(javaImpl);
  }

     *
     * @return the root node of the dependency graph or {@code null} if none
     */
    @Nullable
    Node getRoot();

    /**
     * The ordered list of the flattened dependency nodes.
     *
     * @return the ordered list of the flattened dependency nodes
     */
    @Nonnull
    List<Node> getNodes();

    /**

     * endpoints}) if one is not already present.
     *
     * <p>If this graph is directed, {@code endpoints} must be ordered and the added edge will be
     * directed; if it is undirected, the added edge will be undirected.
     *
     * <p>If this graph is directed, {@code endpoints} must be ordered.
     *
     * <p>If either or both endpoints are not already present in this graph, this method will

    } else {
      return false;
    }
    return comparator.equals(comparator2);
  }

  @SuppressWarnings("unchecked")
  // if sortedSet.comparator() is null, the set must be naturally ordered
  public static <E extends @Nullable Object> Comparator<? super E> comparator(
      SortedSet<E> sortedSet) {
    Comparator<? super E> result = sortedSet.comparator();
    if (result == null) {

    assertThat(graph.hasEdgeConnecting(EndpointPair.ordered(1, 2))).isFalse();
    assertThat(graph.hasEdgeConnecting(EndpointPair.ordered(2, 1))).isFalse();
  }

  @Test
  public void edgeValue_directed_correct() {
    graph = ValueGraphBuilder.directed().build();
    graph.putEdgeValue(1, 2, "A");
    assertThat(graph.edgeValue(EndpointPair.ordered(1, 2))).hasValue("A");
  }

  @Test

  public void testForEachKnownOrder() {
    List<E> elements = new ArrayList<>();
    collection.forEach(elements::add);
    List<E> expected = Helpers.copyToList(getOrderedElements());
    assertEquals("Different ordered iteration", expected, elements);
  }

    } else {
      return false;
    }
    return comparator.equals(comparator2);
  }

  @SuppressWarnings("unchecked")
  // if sortedSet.comparator() is null, the set must be naturally ordered
  public static <E extends @Nullable Object> Comparator<? super E> comparator(
      SortedSet<E> sortedSet) {
    Comparator<? super E> result = sortedSet.comparator();
    if (result == null) {