* be thrown by calling {@code finishToFuture().get()} if this were the last step. Calling {@code
   * cancel()} on the returned future has no effect on the {@code ClosingFuture} pipeline.
   *
   * <p>{@code statusFuture} differs from most methods on {@code ClosingFuture}: You can make calls
   * to {@code statusFuture} <i>in addition to</i> the call you make to {@link #finishToFuture()} or