* EndpointPair [N4, N4] - return
   * Visited Nodes = {N1, N2, N3, N4}
   * </pre>
   */
  private static final class Undirected<N> extends EndpointPairIterator<N> {
    // It's a little weird that we add `null` to this set, but it makes for slightly simpler code.
    @CheckForNull private Set<@Nullable N> visitedNodes;

    private Undirected(BaseGraph<N> graph) {
      super(graph);

@GwtCompatible
@ElementTypesAreNonnullByDefault
final class RelationshipTester<T> {

  static class ItemReporter {
    String reportItem(Item<?> item) {
      return item.toString();
    }
  }

  /**
   * A word about using {@link Equivalence}, which automatically checks for {@code null} and
   * identical inputs: This sounds like it ought to be a problem here, since the goals of this class

  }

  /**
   * A builder for creating immutable map instances, especially {@code public static final} maps
   * ("constant maps"). Example:
   *
   * <pre>{@code
   * static final ImmutableMap<String, Integer> WORD_TO_INT =
   *     new ImmutableMap.Builder<String, Integer>()
   *         .put("one", 1)
   *         .put("two", 2)
   *         .put("three", 3)
   *         .buildOrThrow();
   * }</pre>
   *

        .addEqualityGroup(ImmutableIntArray.of(1, 3))
        .addEqualityGroup(ImmutableIntArray.of(1, 2, 3))
        .testEquals();
  }

  /**
   * This is probably a weird and hacky way to test what we're really trying to test, but hey, it
   * caught a bug.
   */
  public void testTrimmed() {
    ImmutableIntArray iia = ImmutableIntArray.of(0, 1, 3);
    assertDoesntActuallyTrim(iia);

      We could probably have resumed it after https://github.com/google/guava/pull/6664.
      But it's always weird that published poms reference test-only libraries at all, so I'm not in any rush to do so.
      -->
    </dependencies>
  </dependencyManagement>
  <profiles>
    <profile>
        <id>sonatype-oss-release</id>

   * passing a TypeToken<X>. This would be invalid. Maybe we could accept a TypeParameter<@PolyNull
   * X> if we support such a thing? It would be weird or misleading for users to be able to pass
   * `new TypeParameter<@Nullable T>() {}` and have it act as a plain `TypeParameter<T>`, but
   * hopefully no one would do that, anyway. See also the comment on TypeParameter itself.

 *   };</pre>
 *
 * <p>An alternative using Java 8:
 *
 * <pre>{@code
 * return Converter.from(
 *     Integer::toHexString,
 *     s -> parseUnsignedInt(s, 16));
 * }</pre>
 *
 * @author Mike Ward
 * @author Kurt Alfred Kluever
 * @author Gregory Kick
 * @since 16.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
/*

THROUGH the earth!  How funny it'll seem to come out among the
people that walk with their heads downward!  The Antipathies, I
think--' (she was rather glad there WAS no one listening, this
time, as it didn't sound at all the right word) `--but I shall
have to ask them what the name of the country is, you know.
Please, Ma'am, is this New Zealand or Australia?' (and she tried
to curtsey as she spoke--fancy CURTSEYING as you're falling

import java.util.Collection;
import java.util.Map;

/**
 * Test {@link Multimap#asMap()} for an {@link ImmutableSetMultimap} with {@link MapInterfaceTest}.
 *
 * @author Mike Ward
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public class ImmutableSetMultimapAsMapImplementsMapTest
    extends AbstractMultimapAsMapImplementsMapTest {

  public ImmutableSetMultimapAsMapImplementsMapTest() {

      if (useBarriers) {
        firstBarrier.await();
        secondBarrier.await();
      }
    }

    @Override
    protected ScheduledExecutorService executor() {
      // use a bunch of threads so that weird overlapping schedules are more likely to happen.
      return Executors.newScheduledThreadPool(10);
    }

    @Override
    protected Scheduler scheduler() {
      return new CustomScheduler() {