* been cleared by this point.
     */
    reference.clear();

    if (reference == frqReference) {
      /*
       * The client no longer has a reference to the FinalizableReferenceQueue. We can stop.
       */
      return false;
    }

    try {
      finalizeReferentMethod.invoke(reference);
    } catch (Throwable t) {

    if (threadStarted) {
      return;
    }

    Reference<?> reference;
    while ((reference = queue.poll()) != null) {
      /*
       * This is for the benefit of phantom references. Weak and soft references will have already
       * been cleared by this point.
       */
      reference.clear();
      try {
        ((FinalizableReference) reference).finalizeReferent();
      } catch (Throwable t) {

    if (threadStarted) {
      return;
    }

    Reference<?> reference;
    while ((reference = queue.poll()) != null) {
      /*
       * This is for the benefit of phantom references. Weak and soft references will have already
       * been cleared by this point.
       */
      reference.clear();
      try {
        ((FinalizableReference) reference).finalizeReferent();
      } catch (Throwable t) {

    @ParametricNullness private final T reference;

    private Wrapper(Equivalence<? super @NonNull T> equivalence, @ParametricNullness T reference) {
      this.equivalence = checkNotNull(equivalence);
      this.reference = reference;
    }

    /** Returns the (possibly null) reference wrapped by this instance. */
    @ParametricNullness
    public T get() {
      return reference;
    }

    /**

    @ParametricNullness private final T reference;

    private Wrapper(Equivalence<? super @NonNull T> equivalence, @ParametricNullness T reference) {
      this.equivalence = checkNotNull(equivalence);
      this.reference = reference;
    }

    /** Returns the (possibly null) reference wrapped by this instance. */
    @ParametricNullness
    public T get() {
      return reference;
    }

    /**

/** Implementation of an {@link Optional} containing a reference. */
@GwtCompatible
@ElementTypesAreNonnullByDefault
final class Present<T> extends Optional<T> {
  private final T reference;

  Present(T reference) {
    this.reference = reference;
  }

  @Override
  public boolean isPresent() {
    return true;
  }

  @Override
  public T get() {
    return reference;
  }

  @Override

/** Implementation of an {@link Optional} containing a reference. */
@GwtCompatible
@ElementTypesAreNonnullByDefault
final class Present<T> extends Optional<T> {
  private final T reference;

  Present(T reference) {
    this.reference = reference;
  }

  @Override
  public boolean isPresent() {
    return true;
  }

  @Override
  public T get() {
    return reference;
  }

  @Override

    if (successors != null) {
      checkState(successors.add(node));
    }
  }

  @CheckForNull
  private static <T> T getReference(@CheckForNull Reference<T> reference) {
    return (reference == null) ? null : reference.get();
  }

   * for insertions.
   */
  static <E> Set<E> preservesInsertionOrderOnAddsSet() {
    return Sets.newLinkedHashSet();
  }

  static <T> T[] newArray(T[] reference, int length) {
    T[] empty = reference.length == 0 ? reference : Arrays.copyOf(reference, 0);
    return Arrays.copyOf(empty, length);
  }

  /** Equivalent to Arrays.copyOfRange(source, from, to, arrayOfType.getClass()). */

      runTestMethod(NO_UNSAFE);
    } finally {
      Thread.currentThread().setContextClassLoader(oldClassLoader);
    }

    Thread.currentThread().setContextClassLoader(NO_ATOMIC_REFERENCE_FIELD_UPDATER);
    try {
      runTestMethod(NO_ATOMIC_REFERENCE_FIELD_UPDATER);
      // TODO(lukes): assert that the logs are full of errors
    } finally {
      Thread.currentThread().setContextClassLoader(oldClassLoader);
    }
  }