Hi Sayak

This is a sample Grant Handler implementation. To support scopes and customized values, it is required to extend the respective methods. You can find a couple of existing implementations in the attached references.

Furthermore, could you please elaborate more on the error that you are observing? If this is an Internal server error, then the respective error-trace can be found in the API Manager node's carbon logs.

[1]: https://github.com/wso2-extensions/identity-inbound-auth-oauth/blob/master/components/org.wso2.carbon.identity.oauth/src/main/java/org/wso2/carbon/identity/oauth2/token/handlers/grant/AuthorizationGrantHandler.java

[2]: https://github.com/wso2/carbon-apimgt/blob/master/components/apimgt/org.wso2.carbon.apimgt.tokenmgt/src/main/java/org/wso2/carbon/apimgt/tokenmgt/handlers/ExtendedClientCredentialsGrantHandler.java