I use CXF via the features.xml inside of Apache Karaf. I use the umbrella feature "cxf" to pull in most of the CXF bundles.
When upgrading from CXF 2.5.0 to 2.6.0, I started getting errors like the following when my Accepts header is application/json:
I put a breakpoint in org.apache.cxf.jaxrs.provider.ProviderFactory and found this:
Then I looked at the manifest for cxf-rt-frontend-jaxrs and noticed that the Import-Packages line lacks a reference to org.apache.cxf.jaxrs.provider.json and other providers that were moved to the new cxf-rt-rs-extension-providers bundle for 2.6.0.
I think the solution is to simply add an import for org.apache.cxf.jaxrs.provider.json to the manifest of cxf-rt-frontend-jaxrs