$ mvn -pl saga test -Dtest=ChoreographyCompensationTest
(same saga, stock deliberately too low: 1 unit on hand, order asks for 5)

Order 1 status: CANCELLED
Stock remaining for GADGET-1 (untouched by the rejected reservation): 1
Payment record status: REFUNDED

[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0

InventoryChoreographyListener's tryReserve() refused before touching the stock map at all --
the 1 unit is exactly where it started. That rejection published InventoryRejected, which
PaymentChoreographyListener is also subscribed to; it refunded the payment it had reserved
earlier and published PaymentRefunded, which OrderChoreographyListener used to cancel the
order. The compensating transaction (the refund) is ordinary code in a class that already
existed for an unrelated reason -- nothing new coordinates it.