private static LocalProvider createDefaultLocalProvider(String clusterName) {
        return new LocalProvider(emptySearchChainSpecification(clusterName),
                                 new FederationOptions(),
                                 new LocalProviderSpec(clusterName));
    }
Adds default search chains for all local clusters not mentioned explicitly
@author Tony Vaagenes
config-model/src/main/java/com/yahoo/vespa/model/container/search/searchchain/defaultsearchchains/LocalClustersCreator.java