class FastjsonSerializer implements StringSerializer {
    SerializeConfig config;
    SerializerFeature[] features;

    protected FastjsonSerializer(SerializeConfig config, SerializerFeature... features) {
        this.config = config;
        this.features = features;
    }

    @Override
    public String serialize(Object obj) throws IOException {<FILL_FUNCTION_BODY>}
}

        if (config == null) {
            return JSON.toJSONString(obj, features);
        } else {
            return JSON.toJSONString(obj, config, features);
        }
    
<no_super_class>