[Ginger Payments] Is any documentation on the «order_lines» property of the «POST /v1/orders/» request?

The order_lines property is present in the JSON Schema of a «POST /v1/orders/» request but is not used by any of the 6 Ginger Payments plugins nor by any of the 2 Ginger Payments SDKs.
It is also absent on the gingerpayments.com website:

Hello @Joachim_de_Boer, is any documentation on it?

See also:

My example: