if (!isNullOrEmpty(pendingDescription)) {
        builder.append("PENDING, info=[").append(pendingDescription).append("]");
      } else if (isDone()) {
        addDoneString(builder);
      } else {
        builder.append("PENDING");
      }
    }
    return builder.append("]").toString();
  }

  /**

   * implementation. Using a reconstruction of the default Object.toString() prevents OOMs and stack
   * overflows, and helps avoid sensitive data inadvertently ending up in exception messages.
   */
  private void appendResultObject(StringBuilder builder, @CheckForNull Object o) {
    if (o == null) {
      builder.append("null");
    } else if (o == this) {