There is no order_line_id field in API v3 order->lines

v2 - http://puu.sh/A8TBZ/373104de8c.png
v3 - http://puu.sh/A8TAO/d54072d4ac.png

The id is needed from some endpoints, e.g. order/{id}/split

P.S. I can parse it from “link”, but…

Yes, that is correct.