@ExtJson
 @Delete("cities")
 public void destroy(DtoCities dtos) {
   for (DtoCity dto : dtos) {
     final City city = cities.get(dto.getId());
     validate(
         new Validations() {
           {
             that(
                 city.getAddresses().isEmpty(),
                 "constraint",
                 String.format(
                     "city %s belong to any address, then doesn\'t deleted.", city.toString()));
           }
         });
     this.cities.delete(city);
     logger.debug(city.toString() + " removed.");
   }
   json("actor destoyed sucessfully", true);
 }
 @Get("cities")
 public void list() {
   json(new DtoCities(cities.list()));
 }