public static CommonConfigHolder getInstance() {
        if (isInit && instance != null) {
            return instance;
        }
        synchronized (CommonConfigHolder.class) {
            if (!isInit) {
                instance = new CommonConfigHolder();
                if (instance.loadConfigFile()) {
                    instance.preReadFields();
                    LOG.info("{} load and read result is: {}", COMMON_CONFIG_FILE_NAME, instance.toString());
                }
                isInit = true;
            }
        }
        return instance;
    }
get instance for common.properties config manager
inlong-dataproxy/dataproxy-source/src/main/java/org/apache/inlong/dataproxy/config/CommonConfigHolder.java