in play-v29/src/main/scala/com/gu/googleauth/actions.scala [29:32]
def fromJson(json: JsValue): Option[UserIdentity] = json.asOpt[UserIdentity]
def fromRequest(request: RequestHeader): Option[UserIdentity] = {
request.session.get(KEY).flatMap(credentials => UserIdentity.fromJson(Json.parse(credentials)))
}