private List<CommentedSearchChain> commentedSourceProviderSearchChains(SourcesTarget sourcesTarget,
                                                                           SearchChainRegistry registry) {
        List<CommentedSearchChain> commentedSearchChains = new ArrayList<>();
        String ifMatchingSourceRefPrefix = "If source refs contains '" + sourcesTarget.getId() + "' and provider is '";

        commentedSearchChains.add(
                new CommentedSearchChain(ifMatchingSourceRefPrefix + sourcesTarget.defaultProviderSource().provider +
                        "'(or not given).", registry.getChain(sourcesTarget.defaultProviderSource().searchChainId)));

        for (SearchChainInvocationSpec providerSource : sourcesTarget.allProviderSources()) {
            if (!providerSource.equals(sourcesTarget.defaultProviderSource())) {
                commentedSearchChains.add(
                        new CommentedSearchChain(ifMatchingSourceRefPrefix + providerSource.provider + "'.",
                                registry.getChain(providerSource.searchChainId)));
            }
        }
        return commentedSearchChains;
    }
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