@Override
    protected void onReturning(Request request, Processor processor, Response response) {
        super.onReturning(request, processor, response);
        timer.sampleSearchReturn(nextIndex(), context.getDetailedDiagnostics(), (Result)response);
    }
Calls ping on the next search in this chain. If there is no next, a Pong is created and returned.
container-search/src/main/java/com/yahoo/search/searchchain/Execution.java