@Override
    public Collection<CommentedSearchChain> getSearchChainsForwarded(SearchChainRegistry registry) {
        List<CommentedSearchChain> searchChains = new ArrayList<>();

        for (var target : searchChainResolver.allTopLevelTargets()) {
            if (target instanceof SourcesTarget) {
                searchChains.addAll(commentedSourceProviderSearchChains((SourcesTarget)target, registry));
            } else if (target instanceof SingleTarget) {
                searchChains.add(commentedSearchChain((SingleTarget)target, registry));
            } else {
                log.warning("Invalid target type " + target.getClass().getName());
            }
        }

        return searchChains;
    }
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