CreateCustomerInCrmJavaDelegate.java

@Component
public class CreateCustomerInCrmJavaDelegate implements JavaDelegate {

    @Autowired
    private ObjectMapper objectMapper;

    @Autowired
    private CrmFacade crmFacade;
  
    public void execute(DelegateExecution execution) throws Exception {
        // Data Input Mapping
        String customerDataJson = (String) execution.getVariable("customerData");
        CustomerData customerData = objectMapper.readValue(customerDataJson, CustomerData.class);

        // Delegate to business logic
        String customerId = crmFacade.createCustomer(customerData);

        // Data Output Mapping
        execution.setVariable("customerId", customerId);
    }
}

One could use the object mapping of the Spin API to make this look nicer and be closer to how it would look like with Spring Zeebe: https://github.com/camunda-community-hub/camunda-8-process-solution-template/blob/main/src/main/java/org/example/camunda/process/solution/worker/MyWorker.java

I would not try to fit in too much in one go. If they have the code above - that would at least still work if "adapted" - which would be my main point.