I think I know what may be causing this. The org.picketlink.idm.config.Builder is from org.picketlink.idm.api and there is no dependency defined on module org.picketlink.config to org.picketlink.idm.api.

I would suggest you to add org.picketlink.idm.api dependency to org.picketlink.config module. I think that should fix that NCDF.