code: public static String toJsonString(Object object, FieldModifier modifier) throws IllegalAccessException {
          return toJsonString(object, modifier, JsonMethod.AUTO);
      }
docs: 将Bean类指定修饰符的属性转换成JSON字符串
  
  @param object Bean对象
  @param modifier 属性的权限修饰符
  
  @return 没有格式化的JSON字符串
  
  @throws IllegalAccessException 异常