private void addDoneString(StringBuilder builder) {
    try {
      V value = getUninterruptibly(this);
      builder.append("SUCCESS, result=[");
      appendResultObject(builder, value);
      builder.append("]");
    } catch (ExecutionException e) {
      builder.append("FAILURE, cause=[").append(e.getCause()).append("]");
    } catch (CancellationException e) {