code: public synchronized Hosts putAllInRandomOrder(String domain, String[] ips) {
          Random random = new Random();
          int index = (int) (random.nextLong() % ips.length);
          if (index < 0) {
              index += ips.length;
          }
          LinkedList<String> ipList = new LinkedList<String>();
          for (int i = 0; i < ips.length; i++) {
              ipList.add(ips[(i + index) % ips.length]);
          }
          hosts.put(domain, ipList);
          return this;
      }
docs: avoid many server visit first ip in same time.s
  
  @param domain 域名
  @param ips    IP 列表
  @return 当前host 实例