When the billing item was created.
{ "$schema": "https://json-schema.org/draft/2020-12/schema", "$id": "#/components/schemas/bill-subs-api_occurred_at", "title": "bill-subs-api_occurred_at", "description": "When the billing item was created.", "example": "2014-03-01T12:21:59.3456Z", "format": "date-time", "readOnly": true, "type": "string" }