private Execution createForward(Execution execution) {
        Chain<Searcher> targetChain = execution.context().searchChainRegistry().getComponent(target);
        if (targetChain == null) return null;
        return new Execution(targetChain, execution.context());
    }
A lightweight searcher to forward all incoming requests to a single search
chain defined in config. An alternative to federation searcher when standard
semantics are not necessary for the application.

@see FederationSearcher
@author Steinar Knutsen
container-search/src/main/java/com/yahoo/search/federation/ForwardingSearcher.java