org.hibernate.MappingException: composite-id class must implement Serializable:
at org.hibernate.mapping.RootClass.checkCompositeIdentifier(RootClass.java:264)
at org.hibernate.mapping.RootClass.validate(RootClass.java:245)
at org.hibernate.cfg.Configuration.validate(Configuration.java:1193)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1378)
at org.hibernate.cfg.AnnotationConfiguration.buildSessionFactory(AnnotationConfiguration.java:954)