private FederationConfig.Target.SearchChain getProvider(FederationConfig.Target target, String providerName) {
        for (FederationConfig.Target.SearchChain searchChain : target.searchChain()) {
            if (searchChain.providerId().equals(providerName))
                return searchChain;
        }
        fail("No provider " + providerName);
        return null;
    }
Test generated config for federation.
@author Tony Vaagenes
config-model/src/test/java/com/yahoo/vespa/model/container/search/searchchain/FederationTest.java