code: protected Url convertProviderToUrl(ClientTransportConfig transportConfig, ProviderInfo providerInfo) {
          // Url的第一个参数，如果不用事件的话，其实无所谓
          Url boltUrl = new Url(providerInfo.toString(), providerInfo.getHost(), providerInfo.getPort());
  
          boltUrl.setConnectTimeout(transportConfig.getConnectTimeout());
          // 默认初始化connNum个长连接,为了slb和vip的情况
          final int connectionNum = transportConfig.getConnectionNum();
          if (connectionNum > 0) {
              boltUrl.setConnNum(connectionNum);
          } else {
              boltUrl.setConnNum(1);
          }
          boltUrl.setConnWarmup(false); // true的话
          if (RpcConstants.PROTOCOL_TYPE_BOLT.equals(providerInfo.getProtocolType())) {
              boltUrl.setProtocol(RemotingConstants.PROTOCOL_BOLT);
          } else {
              boltUrl.setProtocol(RemotingConstants.PROTOCOL_TR);
          }
          return boltUrl;
      }
docs: For convert provider to bolt url.
  
  @param transportConfig ClientTransportConfig
  @param providerInfo    ProviderInfo
  @return Bolt Url