Camel XMPP communication is not working in version 2.15.3 when running in Karaf. The feature installation works fine but no messages are processed.
I guess this is potentially based on changing the Smack version from 3 to 4.
Based on the existing Camel Karaf tests I created a simple test which passes with Camel Version 2.14.3 and fails with Camel Version 2.15.3. The test can be found here https://github.com/achim86/karaf-xmpp (remember to start the XMPPServer before running the test as described in the readme).