docs: private String getListResultString(List result) {
          StringBuilder sb = new StringBuilder();
          Iterator i = result.iterator();
          if (!i.hasNext()) {
              return "[]";
          }
          sb.append('[');
          for (;;) {
              Object e = i.next();
              // 注意: 修改为getResultString(e)进行递归处理
              sb.append(e == this ? "(this Collection)" : getResultString(e));
              if (!i.hasNext()) {
                  return sb.append(']').toString();
              }
              sb.append(", ");
          }
      }