private void search(Query query, Execution execution, Collection<Target> targets, Result mergedResults) {
        FederationResult results = search(query, execution, targets);
        results.waitForAll((int)query.getTimeLeft(), clock);

        HitOrderer s = null;
        for (FederationResult.TargetResult targetResult : results.all()) {
            if (s == null)
                s = dirtyCopyIfModifiedOrderer(mergedResults.hits(), targetResult.getOrTimeoutError().hits().getOrderer());
            mergeResult(query, targetResult.target, mergedResults, targetResult.getOrTimeoutError());
        }
    }
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