JSON schema "default" in PATCH requests considered harmful

[garethsb]

https://github.com/AMWA-TV/nmos-network-control/blob/v1.0.x/APIs/schemas/network-flow-patch.json has a "default" on "forward_flow". I think this is wrong, since it's unclear, when the client request omits this property, whether the current value is replaced with the default or not. The best thing would be to remove the default in this schema. (The "dscp" property description also still says "default is CS0" even though the default has been removed from that property, so that could also be worth clearing up.)

(Similar issue has previously been dealt with in IS-05: AMWA-TV/is-05#37.)