Orders are marked as cancelled when all line_items within the order are reversed.
{
"id": 572,
"object": "event",
"api_version": "3.2",
"webhook_version": "1.0",
"created_at": "2021-04-11T16:04:58.000000Z",
"type": "order.cancelled",
"data": {
"object": {
"object": "order",
"id": 350,
"postage_value": 0,
"value": 1000,
"account_id": 1
}
}
}