public interface FinalizationPredicate {
    boolean isDone();
  }

  /**
   * Waits until the given weak reference is cleared, invoking the garbage collector as necessary to
   * try to ensure that this will happen.
   *
   * <p>This is a convenience method, equivalent to:
   *
   * <pre>{@code
   * awaitDone(new FinalizationPredicate() {
   *   public boolean isDone() {

  public interface FinalizationPredicate {
    boolean isDone();
  }

  /**
   * Waits until the given weak reference is cleared, invoking the garbage collector as necessary to
   * try to ensure that this will happen.
   *
   * <p>This is a convenience method, equivalent to:
   *
   * <pre>{@code
   * awaitDone(new FinalizationPredicate() {
   *   public boolean isDone() {