return resultString
          + "exceptionType=["
          + localExceptionType
          + "], fallback=["
          + localFallback
          + "]";
    } else if (superString != null) {
      return resultString + superString;
    }
    return null;
  }

  /** Template method for subtypes to actually run the fallback. */
  @ForOverride
  @ParametricNullness

    String superString = super.pendingToString();
    String resultString = "";
    if (localInputFuture != null) {
      resultString = "inputFuture=[" + localInputFuture + "], ";
    }
    if (localFunction != null) {
      return resultString + "function=[" + localFunction + "]";
    } else if (superString != null) {
      return resultString + superString;
    }
    return null;
  }