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 nestedOrder = parseNestedOrder(value, nestedLevels);
        if (nestedOrder) {
          order.push(nestedOrder);
        }
      }
      if (nestedLevels > 0) {
        return order;
      }
      const hiddenGroups = [];
      for (const groupRef of contentGroupRefs) {
        if (parsedOrderRefs.has(groupRef)) {
          continue;
        }
        hiddenGroups.push(groupRef.toString());
      }
      if (hiddenGroups.length) {
        order.push({ name: null, order: hiddenGroups });
      }
      return order;
    }
    function parseNestedOrder(ref, nestedLevels) {
      if (++nestedLevels > MAX_NESTED_LEVELS) {
        warn("parseNestedOrder - reached MAX_NESTED_LEVELS.");
        return null;
      }
      const value = xref.fetchIfRef(ref);
      if (!Array.isArray(value)) {
        return null;
      }