Grails: Protecting REST API with OAuth2.0

I am creating a REST API using Grails. I want it to be protected using the OAuth2.0 client_credentials (grant_type) stream. My use case is as follows:

an external agent will send a request for something like

http://server-url/oauth/token?client_id=clientId&client_secret=clientSecret&grant_type=client_credentials

and get access_token. Then my URL (protected resource) should be accessible with something like

http://server-url/resource?access_token={access-token obtained before}

I am looking for something that makes it easy and fast on Grails. What would be the best way / tool / plugin for this? Scribe library is an option, if there are any tutorials for my specific use case, this will be great.

PS: I tried spring-security and its related plugins, without joy. Any alternatives would be good.