Just spent a while trying to figure out how to add the JAX-RS features repository to Karaf before finally realizing that the artifact was missing the "features" classifier. Obviously not a huge issue. I was able to successfully add the repository using the url mvn:org.apache.aries.jax.js/org.apache.aries.jax.rs.features/1.0.5/xml. Just the same, it was fairly confusing for someone new to Karaf and seeing all the other repositories using urls like mvn:<groupId>/<artifactId>/<version>/xml/features.
Figured I'd throw this out there in case it was an oversight.