I've set productSystemName in OpenAPI CR to "productSystemName" and it propagates to Product and Backend "system_name" as "productsystemname" and to backend usage to

backendUsages:
    productSystemName:
      path: /

which leads to error

 spec.backendUsages[productSystemName]: Invalid value:
        v1beta1.BackendUsageSpec{Path:"/"}: backend usage does not have valid
        backend reference.

HOW

Update the Open API Status to report a validation error. 

Backend CR might need a Status update to a validation message also. 

Can we enforce a syntax in the CRD? see this