Http binding for post request with json body

I’m trying create an http thing for a graphql (post) request. My current thing looks like:

Thing http:url:tibber "Tibber energy" [
	headers="Authorization=Bearer <my token>", "Content-Type=application/json",
	refresh=45] {
			Type string : prices_today "Todays prices" [ stateContent="{ \"query\": \"{viewer {homes {currentSubscription {priceInfo {today {total startsAt} }}}}}\" }" ]

This generates the log messages:

Using the insecure client for thing 'http:url:tibber'.
No authentication configured for thing 'http:url:tibber'
Received HTTP PUT request for update at 'things/http:url:tibber' for an unmanaged thing 'http:url:tibber'.

… and no update for my connected string item. The http binding in debug mode.
I’ve browsed the related postings to no avail. Any kind soul have input?

(My current working plan b is that I have this call in a separate script)