Fetch the list, take the XML from the payload field, acknowledge it.
Pagination
The list is cursor-paginated. When more results exist, the response carries a
nextPageToken that you pass back as the pageToken parameter. The limit
parameter accepts 1 to 100, defaulting to 20.
Acknowledgement
The acknowledge call is idempotent — repeating it is safe. The document
moves from RECEIVED to ACKNOWLEDGED.