getOptionalContentConfig({ intent = "display" } = {}) {
    const { renderingIntent } = this._transport.getRenderingIntent(intent);

    return this._transport.getOptionalContentConfig(renderingIntent);
  }
@param {GetOptionalContentConfigParameters} [params] - Optional content
  config parameters.
@returns {Promise<OptionalContentConfig>} A promise that is resolved with
  an {@link OptionalContentConfig} that contains all the optional content
  groups (assuming that the document has any).