@Override
    public void init() {
        super.init();
        fieldConsumerSettings = new FieldConsumerSettings();
        fieldConsumerSettings.init();
        setGenerator(null, fieldConsumerSettings);
        renderedChildren = null;
        timeSource = System::currentTimeMillis;
        stream = null;
    }
Creates a json renderer using a custom executor.
Using a custom executor is useful for tests to avoid creating new threads for each renderer registry.
container-search/src/main/java/com/yahoo/search/rendering/JsonRenderer.java