Migrating vRA 6.2 extensibility to vRA 7

I'm doing a vRA 7 deployment and I understand that the extensibility has changed and that there is now the Event Broker. While this is very awesome, it's also a bit overwhelming.

What would the equivalent of the below stubs be in vRA 7?

ExternalWFStubs.BuildingMachine

ExternalWFStubs.MachineProvisioned

ExternalWFStubs.BuildingMachine

Thanks!