// Test for EndpointPair class

  @Test
  public void testOrderedEndpointPair() {
    EndpointPair<String> ordered = EndpointPair.ordered("source", "target");
    assertThat(ordered.isOrdered()).isTrue();
    assertThat(ordered).containsExactly("source", "target").inOrder();
    assertThat(ordered.source()).isEqualTo("source");
    assertThat(ordered.target()).isEqualTo("target");

  // Test for EndpointPair class

  @Test
  public void testOrderedEndpointPair() {
    EndpointPair<String> ordered = EndpointPair.ordered("source", "target");
    assertThat(ordered.isOrdered()).isTrue();
    assertThat(ordered).containsExactly("source", "target").inOrder();
    assertThat(ordered.source()).isEqualTo("source");
    assertThat(ordered.target()).isEqualTo("target");

   * Returns {@code true} iff {@code endpoints}' ordering is compatible with the directionality of
   * this graph.
   */
  protected final boolean isOrderingCompatible(EndpointPair<?> endpoints) {
    return endpoints.isOrdered() == this.isDirected();
  }

  protected final <T> Set<T> nodeInvalidatableSet(Set<T> set, N node) {
    return InvalidatableSet.of(