Oauth2 authorise endpoint not encoding goto url causing query params to be lost

When hitting the authorise endpoint with:

rich.example.com:8080/openam/oauth2/authorize?response_type=code&client_id=myClient&scope=mail&redirect_uri=http%3A%2F%2Fexample.com&nonce=12345&state=3445&acr_values=google

The acr value maps the authentication to an auth chain, with a goto param indicating where it should return. This goto url isn't currently being encoded, meaning that the url params are lost.