Encrypted access token (JWE) when using AWS Cognito

I am using Cognito for auth. Is there any way that I can configure it so that the access token is encrypted (JWE instead of JWT)? I can't see any option to configure it as such in the web console or the documentation. I had a look at using the triggers to intercept the token, encrypt it myself on the outbound and decrypt inbound, but I don't think there's a suitable trigger. I guess I'd need a "post-token generation" trigger or something.