The spec for this action:
https://www.adobe.com/content/dam/acom/en/devnet/pdf/pdfs/PDF32000_2008.pdf#G11.2111850
An example of a form using this action:
https://www2.illinois.gov/rev/forms/reg/Documents/reg-1-mr.pdf
if (!this._buttonIcon) {
      this._buttonIcon = [null, null, null];
    }
    this._buttonIcon[nFace] = oIcon;
  }
  checkThisBox(nWidget, bCheckIt = true) {}
  clearItems() {
    if (!this._isChoice) {
      throw new Error("Not a choice widget");
    }
    this._items = [];
    this._send({ id: this._id, clear: null });
  }
  deleteItemAt(nIdx = null) {
    if (!this._isChoice) {
      throw new Error("Not a choice widget");
    }
    if (!this.numItems) {
      return;
    }
    if (nIdx === null) {