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
const storage = this.annotationStorage;
    const id = this.data.id;
    this.container.className = "textWidgetAnnotation";
    let element = null;
    if (this.renderForms) {
      
      
      
      const storedData = storage.getValue(id, {
        value: this.data.fieldValue,
        valueAsString: this.data.fieldValue,
      });
      const textContent = storedData.valueAsString || storedData.value || "";
      const elementData = {
        userValue: null,
        formattedValue: null,
        beforeInputSelectionRange: null,
        beforeInputValue: null,
      };
      if (this.data.multiLine) {
        element = document.createElement("textarea");
        element.textContent = textContent;
      } else {
        element = document.createElement("input");
        element.type = "text";
        element.setAttribute("value", textContent);
      }
      GetElementsByNameSet.add(element);
      element.disabled = this.data.readOnly;