In case someone would like to use classes defined in project/kjar with JPAPlaceholderResolverStrategy it won't work due to:
https://github.com/droolsjbpm/drools/blob/master/drools-persistence-jpa/src/main/java/org/drools/persistence/jpa/marshaller/JPAPlaceholderResolverStrategy.java#L118

since the unmarshal method gives access to class loader it should be then used for call to Class.forName to avoid CNFE