public static void main(String[] s) {
        CybWmsCommoditiesVo cybWmsCommoditiesVo = new CybWmsCommoditiesVo();
        CybItemVo cybItemVo = new CybItemVo();
        cybItemVo.setStockUnit("2134");
        cybWmsCommoditiesVo.setSupplierCode("24234");
        cybWmsCommoditiesVo.setItem(cybItemVo);
        
        String requestBody = JSON.toJSONString(cybWmsCommoditiesVo, filter);
        System.out.print(requestBody);
    }

private static ValueFilter filter = new ValueFilter() {
    @Override
    public Object process(Object obj, String s, Object v) {
        if (v == null)
            return "";
        return v;
    }
};