I am new to GraphQL but I figured out how to issue requests using apex_web_service.make_rest_request. I am working with Oracle 11g so I don’t currently have access to the new JSON features of later versions of Oracle. If you have any questions, I may be able to help anyone with this topic.
I was able to get some of the simpler requests working. Am now working to get variables and mutations working. Regarding variables, are you including them in the body as with the query?? That’s where I am including them now and am recieving ‘Bad Request’ errors