After a few more hours of analysis could access the url.
If it is like this:
https://your-url/api/v2/user/session?oauth_callback=true&service=facebook&code={code_returned}
After a few more hours of analysis could access the url.
If it is like this:
https://your-url/api/v2/user/session?oauth_callback=true&service=facebook&code={code_returned}