The Hibernate ORM jar included in EAP 7.1 has the following element in
the "Import-Package" section of MANIFEST.MF :

javassist;version="[3.20,4)"

But the app servers ships with Javassist version 3.18.1.GA-redhat-2 so this combination wouldn't boot in an OSGi environment.

This entry is generated during the build by inserting the version used at build time. I'd recommend changing the javassist version during build time to 3.18.1.GA-redhat-2, not least to make sure it's compiled with the matching version and the tests are run with the same version.

Additionally I see EAP has some flags to switch javassist version, I believe to accomodate for Java 9 compatibility; to make sure it works with both versions we might want to allow a more relaxed range of versions.