based on testing with https://github.com/scottmarlow/wildfly/tree/WFLY-10520_pr_hack

it's not possible to enable transformer for application in jboss-deployment-structure.xml.

there are probably more issues

1. application has to have dependency on module org.hibernate.bytecodetransfomer (which is ok, users must edit j-d-s.xml anyway) / or org.hibernate.bytecodetransfomer must be global module
2. transformer has private constructor so ClassFileTransformerProcessor cannot instantiate it