Update a selection plan

Overwrites an existing selection plan. The query parameter id identifies the plan; the request body is a wrapper whose json field carries the full plan JSON document as a string (escaped). Update replaces the whole plan, so fetch the current plan with get first, modify it, then send it back here. If the plan JSON also contains an id it must match the query id. Returns the updated plan.

Example body

{
"json": "{"id":"FF784C2A-...","name":"My plan","nodes":[ ... ]}"
}