For the XMC version I use there are two links that gave me some intro into the GraphQL:
https://XMC:8443/nbi/graphql/schema.idl
https://XMC:8443/nbi/graphiql/index.html (make sure to open the panel on the right side):
https://i.snag.gy/l6txLk.jpg
You might also try your luck with GraphQL based NBI (https://:8443/nbi/graphiql/index.html?query=%7B%0A%20%20accessControl%20%7B%0A%20%20%20...) or Reporting SOAP API (https://emc.extremenetworks.com/content/oneview/docs/connect/docs/reporting_web_se...
