Hey,

I've been attempting to implement the new subscriptions REST API and the subscriptions endpoint always fails with the following information:

{"name":"INVALID_REQUEST","message":"Request is not well-formed, syntactically incorrect, or violates schema.","debug_id":"21c938f94cfc1","details":[{"location":"body","issue":"Unrecognized token 'plan_id': was expecting ('true', 'false' or 'null') line: 1, column: 9"}],"links":[]}

Weirdly enough I am able to get it to work with a straight cURL request but when PHP enters the fold it just doesn't. I think it must be a formatting issue somewhere or something else that is missing. Any help would be appreciated, thanks!