Major Description
To be compatible with several Karaf versions, projects (such as Camel or CXF) should remove:
<repositories>mvn:org.apache.karaf.assemblies.features/standard/2.2.0/xml/features</repositories>
It's an expected behavior as the Karaf features are available by default in the Karaf runtime. Only "external" features descriptor should be defined in <repositories/> section.
It means that the features-maven-plugin should "embed" the Karaf features descriptor and use it be default.