address.setStreet("wangshang.RD");
address.setPostCode(310002);
submap4.put("address1", address);
submap4.put("address2", address);
Country country = address.new Country();
country.setProvince("ZheJiang");
address.setCountry(country);
String mapString4 = JSON.toJSONString(submap4, SerializerFeature.WriteClassName,
SerializerFeature.WriteMapNullValue);