/**
   * Performs a {@linkplain java.lang.invoke.VarHandle#compareAndSet compare-and-set} operation on
   * {@link #valueField} of {@code future}.
   */
  static boolean casValue(AbstractFutureState<?> future, @Nullable Object expect, Object update) {
    return ATOMIC_HELPER.casValue(future, expect, update);
  }

  /** Returns the value of the future, using a volatile read. */
  final @Nullable Object value() {
    return valueField;
  }

  /**
   * Performs a {@linkplain java.lang.invoke.VarHandle#compareAndSet compare-and-set} operation on
   * {@link #valueField} of {@code future}.
   */
  static boolean casValue(AbstractFutureState<?> future, @Nullable Object expect, Object update) {
    return ATOMIC_HELPER.casValue(future, expect, update);
  }

  /** Returns the value of the future, using a volatile read. */
  final @Nullable Object value() {
    return valueField;
  }

     * anything that might slow down execution on such a hot path. Given that the methods are only
     * package-private, I feel OK with just not testing them for NPE.
     *
     * Note that testing casValue is particularly dangerous because it uses Unsafe under some
     * versions of Java, and apparently Unsafe can cause SIGSEGV instead of NPE—almost as if it's
     * not safe.
     */
    concat(

     * anything that might slow down execution on such a hot path. Given that the methods are only
     * package-private, I feel OK with just not testing them for NPE.
     *
     * Note that testing casValue is particularly dangerous because it uses Unsafe under some
     * versions of Java, and apparently Unsafe can cause SIGSEGV instead of NPE—almost as if it's
     * not safe.
     */
    concat(

    HONDA,
    POODLE,
  }

  public void testGetIfPresent() {
    assertThat(Enums.getIfPresent(TestEnum.class, "CHEETO")).hasValue(TestEnum.CHEETO);
    assertThat(Enums.getIfPresent(TestEnum.class, "HONDA")).hasValue(TestEnum.HONDA);
    assertThat(Enums.getIfPresent(TestEnum.class, "POODLE")).hasValue(TestEnum.POODLE);

    assertThat(Enums.getIfPresent(TestEnum.class, "CHEETO")).isPresent();

    assertThat(iterable.firstMatch(equalTo("cool"))).hasValue("cool");
    assertThat(iterable.firstMatch(equalTo("pants"))).hasValue("pants");
    assertThat(iterable.firstMatch(Predicates.alwaysFalse())).isAbsent();
    assertThat(iterable.firstMatch(Predicates.alwaysTrue())).hasValue("cool");
  }

  private static final class IntegerValueOfFunction implements Function<String, Integer> {

    graph.putEdgeValue(1, 2, "A");
    assertThat(graph.edgeValue(EndpointPair.unordered(1, 2))).hasValue("A");
  }

  @Test
  public void edgeValue_undirected_backwards() {
    graph = ValueGraphBuilder.undirected().build();
    graph.putEdgeValue(1, 2, "A");
    assertThat(graph.edgeValue(EndpointPair.unordered(2, 1))).hasValue("A");
  }

  @Test
  public void edgeValue_undirected_mismatch() {

  public void testToOptionalEmpty() {
    assertThat(Stream.empty().collect(toOptional())).isEmpty();
  }

  public void testToOptionalSingleton() {
    assertThat(Stream.of(1).collect(toOptional())).hasValue(1);
  }

  public void testToOptionalNull() {
    Stream<@Nullable Object> stream = Stream.of((Object) null);
    assertThrows(NullPointerException.class, () -> stream.collect(toOptional()));
  }

      @SuppressWarnings("unchecked")
      K castKey = (K) key;
      @SuppressWarnings("unchecked") // similar to the above
      V castValue = (V) value;

      alertListenerIfPresent(castKey, castValue, RemovalCause.EXPLICIT);
      remove(key);
      return true;
    }
    return false;
  }

  @Override
  public boolean replace(K key, V oldValue, V newValue) {

  }

  public void testTryFind() {
    Iterable<String> list = newArrayList("cool", "pants");
    assertThat(tryFind(list, equalTo("cool"))).hasValue("cool");
    assertThat(tryFind(list, equalTo("pants"))).hasValue("pants");
    assertThat(tryFind(list, Predicates.alwaysTrue())).hasValue("cool");
    assertThat(tryFind(list, Predicates.alwaysFalse())).isAbsent();
    assertCanIterateAgain(list);
  }