The orm.xml file is an option to use to map your entities instead of using annotations, if you are using annotations then you do not need it.
The persistence.xml should technically list all of the persistent classes using the <class> tag, but if all of your classes are in the same jar file as your persistence.xml, then these will be discovered by default in
JEE,
and in JSE if you set <exclude-unlisted-classes>false</exclude-unlisted-classes>.