When a batch has completed processing, you'll get the event payload as below:
{
"event_type": "batch.finished",
"resource_type": "shipment_batch",
"resource_id": "3ed3d05f-7ba8-404d-97b1-5a50de300001",
"data": {
"started_at": "2023-01-25T11:30:00.000Z",
"finished_at": "2023-01-25T11:31:00.000Z",
"state": "processed",
"items": 2,
"failed_items": 0
}
}