code: private static String convertMap2Pair(Map<String, String> map) {
  
          if (CommonUtils.isEmpty(map)) {
              return StringUtils.EMPTY;
          }
  
          StringBuilder sb = new StringBuilder(128);
          for (Map.Entry<String, String> entry : map.entrySet()) {
              sb.append(getKeyPairs(entry.getKey(), entry.getValue()));
          }
  
          return sb.toString();
      }
docs: 转换 map to url pair
  
  @param map 属性