Exception:
org.hibernate.MappingException: An AnnotationConfiguration instance is required to use <mapping class="..."/>
An AnnotationConfiguration instance is required to use <mapping class="..."/>
this is expected behavior - the user should select "Annotations" or "JPA"
but it will be a nice feature if in the case hibernate.cfg.xml contains <mapping class="...">
"Core" will become disabled or warning (or error) mesage be display.