code: public Subscription cancelSubscription(final Subscription subscription) {
          return doPUT(Subscription.SUBSCRIPTION_RESOURCE + "/" + subscription.getUuid() + "/cancel",
                       subscription, Subscription.class);
      }
docs: Cancel a subscription
  <p>
  Cancel a subscription so it remains active and then expires at the end of the current bill cycle.
  
  @param subscription Subscription object
  @return Subscription