GrantNewAccessTokenFromAuthCode doesn't work

[NicholasAsimov]

So it seems like passing json as a body for /v1/identity/openidconnect/tokenservice request doesn't work anymore.

This request doesn't work:

curl -v 'https://api.sandbox.paypal.com/v1/identity/openidconnect/tokenservice' \
    -H "Content-Type: application/json" \
    -H "Authorization: Bearing <token>" \
    -d '{"grant_type":"authorization_code","code":"<code>","redirect_uri":"<redirect_uri>"}'

response:

{"error_description":"Grant type is null","error":"invalid_grant","correlation_id":"a7087aa10fff1","information_link":"https://developer.paypal.com/docs/api/#errors"}

Where this request using formdata works:

curl -v 'https://api.sandbox.paypal.com/v1/identity/openidconnect/tokenservice' \
    -H "Content-Type: application/x-www-form-urlencoded" \
    -H "Authorization: Basic <base64(clientID:secret)>" \
    -d 'grant_type=authorization_code&code=<code>&redirect_uri=<redirect_uri>' 

Also making GET request with query params also works.

Did I miss something here and I'm incorrect in my assumption? If not, I can provide a pull request that I started to work on. But one issue is that Paypal returns "expire_in" field as a string, so we would need to do something like here for that field where it is a custom type with UnmarshalJSON method: https://github.com/golang/oauth2/blob/master/internal/token.go#L62.

Edit: Also it looks like using a bearing token for authorization doesn't work, but using a basic clientID:secret auth does work. I fixed the cURL example above.

[plutov]

Merged, thanks!