private static MediaType addKnownType(MediaType mediaType) {
    knownTypes.put(mediaType, mediaType);
    return mediaType;
  }

  /*
   * The following constants are grouped by their type and ordered alphabetically by the constant
   * name within that type. The constant name should be a sensible identifier that is closest to the
   * "common name" of the media. This is often, but not necessarily the same as the subtype.
   *

unhappy at the number of executions the Queen had ordered.

  They very soon came upon a Gryphon, lying fast asleep in the
sun.  (IF you don't know what a Gryphon is, look at the picture.)
`Up, lazy thing!' said the Queen, `and take this young lady to
see the Mock Turtle, and to hear his history.  I must go back and
see after some executions I have ordered'; and she walked off,

      // calculation here.
      return (int) ceil(expectedSize / 0.75);
    }
    return Integer.MAX_VALUE; // any large value
  }

  /**
   * Creates a <i>mutable</i>, empty, insertion-ordered {@code LinkedHashMap} instance.
   *
   * <p><b>Note:</b> if mutability is not required, use {@link ImmutableMap#of()} instead.
   *

  }

  @Test
  public void hasEdgeConnecting_mismatch() {
    putEdge(N1, N2);
    assertThat(graph.hasEdgeConnecting(EndpointPair.ordered(N1, N2))).isFalse();
    assertThat(graph.hasEdgeConnecting(EndpointPair.ordered(N2, N1))).isFalse();
  }

  @Test
  public void hasEdgeConnecting_missingNode() {
    // both nodes missing
    assertThat(

        return Spliterators.spliterator(new Object[0], Spliterator.DISTINCT | Spliterator.ORDERED);
      }
      Map<K, V> delegate = delegateOrNull();
      return (delegate != null)
          ? delegate.keySet().spliterator()
          : Spliterators.spliterator(
              requireKeys(), 0, size, Spliterator.DISTINCT | Spliterator.ORDERED);
    }

    @Override
    public void forEach(Consumer<? super K> action) {

    setDistinctValues(NetworkBuilder.class, networkBuilderA, networkBuilderB);
    setDistinctValues(Network.class, IMMUTABLE_NETWORK_A, IMMUTABLE_NETWORK_B);
    setDefault(EndpointPair.class, EndpointPair.ordered("A", "B"));
  }

  @Override
  public void testNulls() throws Exception {
    try {
      super.testNulls();
    } catch (AssertionError e) {

    // TODO(lowasser): consider an implementation that can support SUBSIZED
    boolean isParallel = false;
    int characteristics = Spliterator.ORDERED | Spliterator.SIZED | Spliterator.NONNULL;
    long estimatedSize = 0L;
    ImmutableList.Builder<Spliterator<? extends T>> splitrsBuilder =
        new ImmutableList.Builder<>(streams.length);

 */
@NullUnmarked
public abstract class AbstractStandardUndirectedNetworkTest extends AbstractNetworkTest {
  private static final EndpointPair<Integer> ENDPOINTS_N1N2 = EndpointPair.ordered(N1, N2);
  private static final EndpointPair<Integer> ENDPOINTS_N2N1 = EndpointPair.ordered(N2, N1);

  @After
  public void validateUndirectedEdges() {
    for (Integer node : network.nodes()) {
      new EqualsTester()
          .addEqualityGroup(

      }

      @Override
      public long estimateSize() {
        return delegate.estimateSize();
      }

      @Override
      public int characteristics() {
        return Spliterator.ORDERED
            | Spliterator.SIZED
            | Spliterator.SUBSIZED
            | extraCharacteristics;
      }

      @Override
      public @Nullable Comparator<? super T> getComparator() {

  @Override
  @GwtIncompatible // Spliterator
  Spliterator<Entry<K, V>> entrySpliterator() {
    return CollectSpliterators.map(
        delegate.entrySet().spliterator(),
        Spliterator.DISTINCT | Spliterator.ORDERED | Spliterator.IMMUTABLE | Spliterator.NONNULL,
        Maps::unmodifiableEntry);
  }

  @Override
  public void forEach(BiConsumer<? super K, ? super V> action) {
    delegate.forEach(action);
  }