docs: public final void addServer(String hostList) throws IOException {
      Map<InetSocketAddress, InetSocketAddress> addresses = AddrUtil.getAddressMap(hostList);
      if (addresses != null && addresses.size() > 0) {
        for (Map.Entry<InetSocketAddress, InetSocketAddress> entry : addresses.entrySet()) {
          final InetSocketAddress mainNodeAddr = entry.getKey();
          final InetSocketAddress standbyNodeAddr = entry.getValue();
          this.connect(new InetSocketAddressWrapper(mainNodeAddr,
              this.serverOrderCount.incrementAndGet(), 1, null));
          if (standbyNodeAddr != null) {
            this.connect(new InetSocketAddressWrapper(standbyNodeAddr,
                this.serverOrderCount.incrementAndGet(), 1, mainNodeAddr));
          }
        }
      }
    }