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();
    }
convert map to url pair

@param map
@return url paramters
registry/registry-sofa/src/main/java/com/alipay/sofa/rpc/registry/sofa/SofaRegistryHelper.java