combiner = null;
    // combiner should be collected even if the future it returns never completes.
    GcFinalization.awaitClear(combinerRef);
  }

  /*
   * TODO(cpovirk): maybe pass around TestFuture instances instead of
   * ListenableFuture instances
   */

  /**
   * A future in {@link TestFutureBatch} that also has a name for debugging purposes and a {@code

    combiner = null;
    // combiner should be collected even if the future it returns never completes.
    GcFinalization.awaitClear(combinerRef);
  }

  /*
   * TODO(cpovirk): maybe pass around TestFuture instances instead of
   * ListenableFuture instances
   */

  /**
   * A future in {@link TestFutureBatch} that also has a name for debugging purposes and a {@code