private static FederationSearcherModel federationSearcherModel() {
        return new FederationSearcherModel(new ComponentSpecification("federation"),
                                           Dependencies.emptyDependencies(),
                                           List.of(),
                                           true);
    }
Defines the searcher models used in the vespa and native search chains, except for federation.

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