Currently compensations bootstrap happens in the transactions subsystem. It registers deployment processor to scan the annotations and add the dependencies if necessary. This is not expensive and doesn't cause any issues other than adding the dependencies to the transactions subsystem. However, I'm currently finishing off the recovery implementation and more bootstrap logic will be needed. In addition, two more recovery modules will have to be registered: one for the participant (a new one) and one for the coordinator (from XTS). This will require to add XTS dependency too.
The whole compensations bootstrapping will not need a lot of code. However, I'm thinking maybe it would be good to pull it out to the separate subsystem in order to maintain the separation of concerns.