checkNotNull(edge);
    checkNotNull(node);

    if (isSelfLoop) {
      checkPositive(++selfLoopCount);
    }
    N previousNode = inEdgeMap.put(edge, node);
    checkState(previousNode == null);
  }

  @Override
  public void addOutEdge(E edge, N node) {
    checkNotNull(edge);
    checkNotNull(node);

    N previousNode = outEdgeMap.put(edge, node);

   */
  SubscriberExceptionContext(
      EventBus eventBus, Object event, Object subscriber, Method subscriberMethod) {
    this.eventBus = checkNotNull(eventBus);
    this.event = checkNotNull(event);
    this.subscriber = checkNotNull(subscriber);
    this.subscriberMethod = checkNotNull(subscriberMethod);
  }

  /**
   * @return The {@link EventBus} that handled the event and the subscriber. Useful for broadcasting

  private final BiPredicate<? super R, ? super R> equivalence;

  private CollectorTester(
      Collector<T, A, R> collector, BiPredicate<? super R, ? super R> equivalence) {
    this.collector = checkNotNull(collector);
    this.equivalence = checkNotNull(equivalence);
  }

  /**
   * Different orderings for combining the elements of an input array, which must all produce the
   * same result.
   */
  enum CollectStrategy {

  @GwtIncompatible
  public Class<V> valueType() {
    return valueTypeOrObjectUnderJ2cl;
  }

  @Override
  K checkKey(K key) {
    return checkNotNull(key);
  }

  @Override
  V checkValue(V value) {
    return checkNotNull(value);
  }

  /**
   * @serialData the key class, value class, number of entries, first key, first value, second key,
   *     second value, and so on.
   */

  @GwtIncompatible
  public Class<V> valueType() {
    return valueTypeOrObjectUnderJ2cl;
  }

  @Override
  K checkKey(K key) {
    return checkNotNull(key);
  }

  @Override
  V checkValue(V value) {
    return checkNotNull(value);
  }

  /**
   * @serialData the key class, value class, number of entries, first key, first value, second key,
   *     second value, and so on.
   */

  }

  @Override
  public T or(T defaultValue) {
    checkNotNull(defaultValue, "use Optional.orNull() instead of Optional.or(null)");
    return reference;
  }

  @Override
  public Optional<T> or(Optional<? extends T> secondChoice) {
    checkNotNull(secondChoice);
    return this;
  }

  @Override
  public T or(Supplier<? extends T> supplier) {
    checkNotNull(supplier);
    return reference;
  }

  @Override

    this.singleRowKey = checkNotNull(rowKey);
    this.singleColumnKey = checkNotNull(columnKey);
    this.singleValue = checkNotNull(value);
  }

  SingletonImmutableTable(Cell<R, C, V> cell) {
    this(cell.getRowKey(), cell.getColumnKey(), cell.getValue());
  }

  @Override
  public ImmutableMap<R, V> column(C columnKey) {
    checkNotNull(columnKey);
    return containsColumn(columnKey)

  public void callAndAssertThrows(
      Class<? extends Throwable> expected, String methodName, Object... arguments)
      throws Exception {
    checkNotNull(expected);
    checkNotNull(methodName);
    checkNotNull(arguments);
    sendRequest(methodName, arguments);
    assertEquals(expected, getResponse(methodName).getThrowable().getClass());
  }

  /**

  @CanIgnoreReturnValue // TODO(kak): consider removing this
  @Override
  public <T> T newProxy(
      T target, Class<T> interfaceType, long timeoutDuration, TimeUnit timeoutUnit) {
    checkNotNull(target);
    checkNotNull(interfaceType);
    checkNotNull(timeoutUnit);
    return target; // ha ha
  }

  @CanIgnoreReturnValue // TODO(kak): consider removing this
  @Override
  @ParametricNullness

    checkNotNull(edge);
    checkNotNull(node);

    if (isSelfLoop) {
      checkPositive(++selfLoopCount);
    }
    N previousNode = inEdgeMap.put(edge, node);
    checkState(previousNode == null);
  }

  @Override
  public void addOutEdge(E edge, N node) {
    checkNotNull(edge);
    checkNotNull(node);

    N previousNode = outEdgeMap.put(edge, node);