exportXfdf abstract method
Exports annotations as an XFDF string.
If pageIndex is provided, only annotations on that page are included.
Note: This returns the XFDF content as a string. In previous versions (Pigeon API) this wrote to a file path — that signature has changed in v6.0.0. Callers are responsible for persisting the string if needed.
Implementation
Future<String> exportXfdf({int? pageIndex});