private void warnIfUnresolvedSearchChains(List<String> errorMessages, HitGroup errorHitGroup) {
        if (!errorMessages.isEmpty()) {
            errorHitGroup.addError(missingSearchChainsErrorMessage(errorMessages));
        }
    }
The name of the query property containing the source name added to the query to each source by this
container-search/src/main/java/com/yahoo/search/federation/FederationSearcher.java