code: public String getPeerPublicHostName (String nodeName)
      {
          if (Objects.equal(_nodeName, nodeName)) {
              return _self.publicHostName;
          }
          PeerNode peer = _peers.get(nodeName);
          return (peer == null) ? null : peer.getPublicHostName();
      }
docs: Returns the public hostname to use when connecting to the specified peer or null if the peer
  is not currently connected to this server.