Getting the value for a header GUC on PostgreSQL v14 is done using `current_setting('request.headers')::json->>'name-of-header'` and in a similar way for `request.cookies` and `request.jwt.claims`
PostgreSQL versions below 14 can opt in to the new JSON GUCs by setting the `db-use-legacy-gucs` config option to false (true by default)
This is enabled by adding `!inner` to the embedded resource
/projects?select=*,clients!inner(*)&clients.id=eq.12
This behaviour can be enabled by default with the config option
db-embed-default-join='inner'
Which saves the need for specifying `!inner` on every request.
If this is enabled, the previous behavior can be restored
per request by specifying `!left` on the embedded resource.
/projects?select=*,clients!left(*)&clients.id=eq.12`
Tested on M20/02M/M2M relationships, views, RPC.
* openapi-mode="follow-acl"(default): follows access control for the
JWT role.
* openapi-mode="ignore-acl": ignores access control for the JWT role.
* openapi-mode="disabled": disables OpenAPI output, the root endpoint
replies with 404 Not Found.
steve-chavez