code: private Object getItem(String key, Type type) {
          if (null == map) {
              return null;
          }
          if (null == type) {
              return map.get(key);
          }
          return Mapl.maplistToObj(map.get(key), type);
      }
docs: 读取一个配置项, 并转换成相应的类型.
  
  @param key
  @param type
  @return