private static void addSources(ComponentRegistry<SearchChain> chains, Provider provider) {
         for (Source source : provider.getSources()) {
             chains.register(source.getId(), source);
         }
     }
Root config producer of the whole search chains model (contains searchchains and searchers).

@author Tony Vaagenes
config-model/src/main/java/com/yahoo/vespa/model/container/search/searchchain/SearchChains.java