Create a Request in Facebook SDK 4 (Android)

As I understand, Facebook SDK v4 doesn't use the Session anymore, but I read in their Graph API document, the session is still used to create the Request

http://ift.tt/1F9cqHf

/* make the API call */
new Request(
    session,
    "/me",
    null,
    HttpMethod.GET,
    new Request.Callback() {
        public void onCompleted(Response response) {
            /* handle the result */
        }
    }
).executeAsync();

It's confusing me, and how can I get the session for Request? Any latest example to get the user profile data by using Facebook Graph API?

Any advice is appreciated.