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 encrypt = this.xref.trailer.get("Encrypt");
    if (!isDict(encrypt)) {
      return null;
    }
    let flags = encrypt.get("P");
    if (!isNum(flags)) {
      return null;
    }
    
    
    
    flags += 2 ** 32;
    const permissions = [];
    for (const key in PermissionFlag) {
      const value = PermissionFlag[key];
      if (flags & value) {
        permissions.push(value);
      }
    }
    return permissions;
  }
  get optionalContentConfig() {