This functional test class seems a little sparse. It currently includes tests for `PaymentsResource.updatePayment()` with credit card and `PaymentsResource.createPayment()` with credit card refund payment types. It does not at all test the `PaymentsResource.getPayment()` endpoint. Considering these are payments, I would think we might include a more complete set of tests including all endpoints and possibly all payment types, at least via one or the other of create or update.