addFormElement(child, indexToInsertAt) {
      super.addFormElement(/** @type {FormControl} */ child, indexToInsertAt);
      // we need to adjust the elements being registered
      /* eslint-disable no-param-reassign */
      child.id = child.id || `${this.localName}-option-${uuid()}`;

      if (this.disabled) {
        child.makeRequestToBeDisabled();
      }

      // TODO: small perf improvement could be made if logic below would be scheduled to next update,
      // so it occurs once for all options
      this.__setAttributeForAllFormElements('aria-setsize', this.formElements.length);
      this.formElements.forEach((el, idx) => {
        el.setAttribute('aria-posinset', idx + 1);
      });

      this.__proxyChildModelValueChanged(
        /** @type {CustomEvent & { target: FormControlHost & LionOption; }} */ ({ target: child }),
      );
      this.resetInteractionState();
      /* eslint-enable no-param-reassign */
    }
@enhance FormRegistrarMixin: make sure children have specific default states when added
@param {FormControlHost & LionOption} child
@param {Number} indexToInsertAt