grant_type=urn%3Aietf%3Aparams%3Aoauth%3Agrant-type%3Atoken-exchange&subject_token=h.p.s&subject_token_type=urn%3Aietf%3Aparams%3Aoauth%3Atoken-type%3Ajwt&audience=https%3A%2F%2Frp.example%2Fapi
