public double getQuotaUsageRate(ApplicationId applicationId) {
        var application = getApplication(applicationId);
        return application.getModel().provisioned().capacities().values().stream()
                .map(Capacity::maxResources)// TODO: This may be unspecified -> 0
                .mapToDouble(resources -> resources.nodes() * resources.nodeResources().cost())
                .sum();
    }
Gets the active Session for the given application id.

@return the active session, or null if there is no active session for the given application id.
configserver/src/main/java/com/yahoo/vespa/config/server/ApplicationRepository.java