I'm setting up an HTTP source in ArcGIS Velocity (ArcGIS Online) and trying to configure OAuth against a third-party API. The token endpoint takes a GET with a Basic auth header and returns the authorization token successfully — HTTP 200, valid token — but it comes back as a bare bearer token with Content-Type text/plain. There's no JSON wrapper at all, just the raw JWT string in the response body.
The snag is the "Identify fields from a sample access token request" step, which asks for the key of the access-token JSON field (e.g. access_token). Since the response isn't JSON and has no key, there's nothing valid to enter, and the test fails with: "Test request failed. Check your token request configuration as well as if your API supports the HTTP OPTIONS method, or alternatively manually configure the response."
Is there any supported way to have Velocity's OAuth consume a plain-text bearer token, or to point the access-token field at the raw response body instead of a JSON key? Or is the only path to stand up a proxy that wraps the token as {"access_token": "..."} so Velocity can parse it? Any guidance or examples for non-JSON token endpoints would be much appreciated.
