With WFLY-18544 addressed from WildFly 31.0.0.Final+, which tries to avoid deployment archives duplication to save disk usage, it has side effects on cases of VFS API usage in the application and/or layered projects.
Main issue is that the jar sub deployments are missing from the tmp/vfs/deployment folder, which exist only under tmp/vfs/temp/ folder, I did some testing using quickstarts against latest WildFly 35.0.0.1.Final. I found the following behavior:
| deployment | tmp/vfs/temp | tmp/vfs/deployment |
|---|---|---|
| war | ✅ (exploded ) | ❌ |
| jar | ❌ | ❌ (Only under data/content/) |
| ear | ✅ (jars are extracted out of ear as sub deployments) | ❌ |
| jar in war | ✅ | ❌ (an empty contents folder) |
| jar in ear | ✅ | ❌ (an empty contents folder) |
| war in ear | ❌ | ✅ (exploded) |
| jar in war that in ear | ✅ | ❌ (an empty contents folder) |
I am not sure if the behaviors above are expected or not since there are different voices.