assertContentsAnyOrder(multimap().asMap().get(null), getValueForNullKey());
  }

  @MapFeature.Require(ALLOWS_NULL_KEY_QUERIES)
  public void testAsMapGetNullKeyAbsent() {
    assertNull(multimap().asMap().get(null));
  }

  @MapFeature.Require(absent = ALLOWS_NULL_KEY_QUERIES)
  public void testAsMapGetNullKeyUnsupported() {
    assertThrows(NullPointerException.class, () -> multimap().asMap().get(null));
  }

          public @Nullable Void call() throws Exception {
            // adds two nanoseconds to the ticker
            ticker.advance(1L);
            Thread.sleep(10);
            ticker.advance(1L);
            return null;
          }
        });

    assertEquals(numberOfThreads * 2, ticker.read());
  }

  @GwtIncompatible // concurrency

  public void testConcurrentAutoIncrementStep() throws Exception {

@Beta
public interface MutableNetwork<N, E> extends Network<N, E> {

  /**
   * Adds {@code node} if it is not already present.
   *
   * <p><b>Nodes must be unique</b>, just as {@code Map} keys must be. They must also be non-null.
   *
   * @return {@code true} if the network was modified as a result of this call
   */
  @CanIgnoreReturnValue
  boolean addNode(N node);

  /**
   * Adds {@code edge} connecting {@code nodeU} to {@code nodeV}.

    Function<N, V> successorNodeToValueFn =
        (N successorNode) ->
            // requireNonNull is safe because the endpoint pair comes from the graph.
            requireNonNull(graph.edgeValueOrDefault(node, successorNode, null));
    return graph.isDirected()
        ? DirectedGraphConnections.ofImmutable(
            node, graph.incidentEdges(node), successorNodeToValueFn)
        : UndirectedGraphConnections.ofImmutable(

    Class<?> rawType = type.getRawType();
    List<Object> samples = sampleInstances.get(rawType);
    Object sample = pickInstance(samples, null);
    if (sample != null) {
      return sample;
    }
    if (rawType.isEnum()) {
      return pickInstance(rawType.getEnumConstants(), null);
    }
    if (type.isArray()) {
      TypeToken<?> componentType = requireNonNull(type.getComponentType());

        return of(element);
      default:
        return new RegularImmutableList<E>(ImmutableList.<E>nullCheckedList(elements));
    }
  }

  // Factory method that skips the null checks.  Used only when the elements
  // are guaranteed to be non-null.
  static <E> ImmutableList<E> unsafeDelegateList(List<? extends E> list) {
    switch (list.size()) {
      case 0:
        return of();
      case 1:

        this(messageCode, new Object[0], null);
    }

    /**
     * Creates {@link ClRuntimeException}.
     *
     * @param messageCode message code
     * @param args arguments for messages
     */
    public ClRuntimeException(final String messageCode, final Object[] args) {
        this(messageCode, args, null);
    }

    /**
     * Creates {@link ClRuntimeException}.
     *

final class RegularImmutableList<E> extends ImmutableList<E> {
  static final ImmutableList<Object> EMPTY = new RegularImmutableList<>(new Object[0], 0);

  // The first `size` elements are non-null.
  @VisibleForTesting final transient @Nullable Object[] array;
  private final transient int size;

  RegularImmutableList(@Nullable Object[] array, int size) {
    this.array = array;
    this.size = size;
  }

 * support even a "normal" `TypeParameter<T>` when `<T>` has a nullable bound. (See the discussion
 * on TypeToken.where.) So, in the interest of failing fast and encouraging the user to switch to a
 * non-null bound if possible, let's require a non-null bound here.
 *
 * TODO(cpovirk): Elaborate on "wouldn't behave as users might expect."
 */
public abstract class TypeParameter<T> extends TypeCapture<T> {

  final TypeVariable<?> typeVariable;

        @SuppressWarnings("rawtypes") // using raw types to avoid a bug in our nullness checker :(
        InternalEntry entry = map.getEntry(sample);
        if (entry != null) {
          Object canonical = entry.getKey();
          if (canonical != null) { // only matters if weak/soft keys are used
            // The compiler would know this is safe if not for our use of raw types (see above).
            @SuppressWarnings("unchecked")