if (throwable != null) {
        return new Failure(throwable);
      }
    }
    boolean wasCancelled = future.isCancelled();
    // Don't allocate a CancellationException if it's not necessary
    if (!GENERATE_CANCELLATION_CAUSES & wasCancelled) {
      /*
       * requireNonNull is safe because we've initialized CAUSELESS_CANCELLED if