code: public ClientFactoryBuilder connectTimeoutMillis(long connectTimeoutMillis) {
          checkArgument(connectTimeoutMillis > 0,
                        "connectTimeoutMillis: %s (expected: > 0)", connectTimeoutMillis);
          return channelOption(ChannelOption.CONNECT_TIMEOUT_MILLIS,
                               ConvertUtils.safeLongToInt(connectTimeoutMillis));
      }
docs: Sets the timeout of a socket connection attempt in milliseconds.