Function encode_order_status_report 

pub fn encode_order_status_report(
    message: &OrderStatusReport,
) -> Result<EncodedPayload, EncodeError>

Encodes an [OrderStatusReport] into canonical bytes plus its venue_order_id index and, when present, its client_order_id index.

External orders observed only at the venue may not carry a client_order_id; the index is omitted in that case so the secondary index never records an empty key.

Errors

Returns an error if MessagePack rejects the payload.