To achieve what you want you need to use Unmanaged Associations with an explicit ON condition, instead of using Managed Associations, which automatically generate foreign key fields. You can read about the difference in the documentation:Unmanaged As...
Another problem might be that you are actually debugging the Maven process and not the Spring Boot process launched by the Maven process. However I'd as Robin suggested also highly suggest simply launching the Application class directly from your IDE...
When using CAP Java simply set logger "com.sap.cds.persistence.sql" to "DEBUG", for example in application.yaml:logging.level:
com.sap.cds.persistence.sql: DEBUG
No, for the reasons Hans-Joachim explained very well. You should rather solve it (as also suggested by Hans-Joachim) by explicitly exposing items in your service.
You didn't provide the definition of your service, but my guess would be that you didn't expose items explicitly in the service, but only Order. Because items are only associated with Order through an association path and not a composition path, they...
