We need a way to disable metadata scanning. It takes too much time on startup.
There is the persistence.xml element exclude-unlisted-classes and the hibernate option hibernate.archive.autodetection but they don't disable the time consuming class/hbm scan for entity mapping metadata.
Possible solution is to implement a Scanner that returns empty ScanResult and pass it on hibernate.archive.scanner. The pull request does this with DisabledScanner.
Usage: In persistence.xml set the property hibernate.archive.scanner as follows.