private SearchChainRegistry createSearchChainRegistry(ComponentRegistry<Searcher> searchers,
                                                          ChainsConfig chainsConfig) {
        SearchChainRegistry searchChainRegistry = new SearchChainRegistry(searchers);
        ChainsModel chainsModel = ChainsModelBuilder.buildFromConfig(chainsConfig);
        ChainsConfigurer.prepareChainRegistry(searchChainRegistry, chainsModel, searchers);
        searchChainRegistry.freeze();
        return searchChainRegistry;
    }
Provides creation of fully configured query Execution instances.
Have an instance of this injected if you need to execute queries which are not initiated from
an external request.

@author bratseth
container-search/src/main/java/com/yahoo/search/searchchain/ExecutionFactory.java