@Override
        public Result search(Query query, Execution execution) {
            Result result = execution.search(query);
            Hit hit0 = new Hit("hit:0");
            Hit hit1 = new Hit("hit:1");
            if (fillableHits) {
                hit0.setFillable();
                hit1.setFillable();
            }
            result.hits().add(hit0);
            result.hits().add(hit1);
            return result;
        }
If true, simulate parallel execution by cloning the query
container-search/src/test/java/com/yahoo/search/searchchain/test/TraceTestCase.java