// Retrieve
Subscription retrievedSub = customer.getSubscriptions().retrieve(sub.getId());
assertEquals(sub.getId(), retrievedSub.getId());
// List
CustomerSubscriptionCollection list = customer.getSubscriptions().all(null);
assertEquals(1, list.getData().size());
assertEquals(sub.getId(), list.getData().get(0).getId());
// Update
Map<String, Object> subUpdateParams = new HashMap<String, Object>();
subUpdateParams.put("plan", plan2.getId());
sub = sub.update(subUpdateParams);