drools-karaf-features-6.0.3-redhat-4-features.xml from droolsjbpm-integration contains the line:

<bundle>mvn:org.jboss.spec.javax.jms/jboss-jms-api_1.1_spec/</bundle>

Because no version is present, builds using this as a dependency will fail with the error:

[ERROR] Failed to execute goal org.apache.karaf.tooling:features-maven-plugin:2.3.3:add-features-to-repo (add-features-to-repo) on project switchyard-karaf-tests: Cannot find version for: org.jboss.spec.javax.jms/jboss-jms-api_1.1_spec/ -> [Help 1]