class DistOptions extends OptionHolder {

    private DistOptions() {
        super();
    }

    private static volatile DistOptions instance;

    public static synchronized DistOptions instance() {<FILL_FUNCTION_BODY>}

    public static final ConfigListOption<String> BACKENDS =
            new ConfigListOption<>(
                    "backends",
                    "The all data store type.",
                    disallowEmpty(),
                    "memory"
            );
}

        if (instance == null) {
            instance = new DistOptions();
            instance.registerOptions();
        }
        return instance;
    
<no_super_class>