@Jens I've created 
SMACK-576 about making smack-resolver-javax an OSGi ServiceComponent.
I wonder why I didn't think about it when we made smack-experimental, smack-extensions and smack-legacy an ServiceComponent. As of Smack 4.0.0 OSGi users would need to manually install smack-resolver-javax. This shouldn't be the case any more with Smack 4.0.1-SNAPSHOT. Could you verify this? Thank you.