code: public Subscription reactivateSubscription(final Subscription subscription) {
          return doPUT(Subscription.SUBSCRIPTION_RESOURCE + "/" + subscription.getUuid() + "/reactivate",
                       subscription, Subscription.class);
      }
docs: Reactivating a canceled subscription
  <p>
  Reactivate a canceled subscription so it renews at the end of the current bill cycle.
  
  @param subscription Subscription object
  @return Subscription