apollo-client/src/main/java/com/ctrip/framework/apollo/util/ConfigUtil.java/ConfigUtil/initConnectTimeout
class ConfigUtil:  private void initConnectTimeout() {
    String customizedConnectTimeout = System.getProperty("apollo.connectTimeout");
    if (!Strings.isNullOrEmpty(customizedConnectTimeout)) {
      try {
        connectTimeout = Integer.parseInt(customizedConnectTimeout);
      } catch (Throwable ex) {
        logger.error("Config for apollo.connectTimeout is invalid: {}", customizedConnectTimeout);
      }
    }
  }