When I point runtime detection to my cdk folder, it will not detect anything.
I had the openshift.cdk feature installed.

nattura:features rasp$ ls|grep cdk
org.jboss.tools.openshift.cdk.feature_3.1.0.Beta1-v20151202-0847-B100

And the runtime detection preference page shows that it will search for cdk runtimes
(CDK is checked).

The cdk in the folder that I use work fine when I add the adapter manually.