private void preReadFields() {
        String tmpValue;
        // read cluster tag
        tmpValue = this.props.get(KEY_PROXY_CLUSTER_TAG);
        if (StringUtils.isNotBlank(tmpValue)) {
            this.clusterTag = tmpValue.trim();
        }
        // read cluster name
        tmpValue = this.props.get(KEY_PROXY_CLUSTER_NAME);
        if (StringUtils.isNotBlank(tmpValue)) {
            this.clusterName = tmpValue.trim();
        }
        // read cluster incharges
        tmpValue = compatGetValue(this.props,
                KEY_PROXY_CLUSTER_INCHARGESV2, KEY_PROXY_CLUSTER_INCHARGES);
        if (StringUtils.isNotEmpty(tmpValue)) {
            this.clusterIncharges = tmpValue.trim();
        }
        tmpValue = compatGetValue(this.props,
                KEY_PROXY_CLUSTER_EXT_TAGV2, KEY_PROXY_CLUSTER_EXT_TAG);
        if (StringUtils.isNotEmpty(tmpValue)) {
            this.clusterExtTag = tmpValue.trim();
        }
        // read the manager setting
        this.preReadManagerSetting();
        // read the configuration related to the default topics
        this.preReadDefTopicSetting();
        // read enable whitelist
        tmpValue = compatGetValue(this.props,
                KEY_ENABLE_WHITELISTV2, KEY_ENABLE_WHITELIST);
        if (StringUtils.isNotBlank(tmpValue)) {
            this.enableWhiteList = "TRUE".equalsIgnoreCase(tmpValue.trim());
        }
        // read max response after save timeout
        tmpValue = this.props.get(KEY_MAX_RAS_TIMEOUT_MS);
        if (StringUtils.isNotEmpty(tmpValue)) {
            this.maxResAfterSaveTimeout = NumberUtils.toLong(tmpValue.trim(), VAL_DEF_MAX_RAS_TIMEOUT_MS);
        }
        // read default buffer queue size
        tmpValue = compatGetValue(this.props,
                KEY_DEF_BUFFERQUEUE_SIZE_KBV2, KEY_DEF_BUFFERQUEUE_SIZE_KB);
        if (StringUtils.isNotEmpty(tmpValue)) {
            this.defBufferQueueSizeKB = NumberUtils.toInt(
                    tmpValue.trim(), VAL_DEF_BUFFERQUEUE_SIZE_KB);
        }
        // read cache cluster selector
        tmpValue = compatGetValue(this.props,
                KEY_CACHE_CLUSTER_SELECTORV2, KEY_CACHE_CLUSTER_SELECTOR);
        if (StringUtils.isNotBlank(tmpValue)) {
            this.cacheClusterSelector = tmpValue.trim();
        }
        // read event handler
        tmpValue = this.props.get(KEY_EVENT_HANDLER);
        if (StringUtils.isNotBlank(tmpValue)) {
            this.eventHandler = tmpValue.trim();
        }
        // read proxy node id
        tmpValue = compatGetValue(this.props,
                KEY_PROXY_NODE_IDV2, KEY_PROXY_NODE_ID);
        if (StringUtils.isBlank(tmpValue)) {
            this.proxyNodeId = AddressUtils.getSelfHost();
        } else {
            this.proxyNodeId = tmpValue.trim();
        }
        // read prometheus Http Port
        tmpValue = compatGetValue(this.props,
                KEY_PROMETHEUS_HTTP_PORTV2, KEY_PROMETHEUS_HTTP_PORT);
        if (StringUtils.isNotBlank(tmpValue)) {
            this.prometheusHttpPort = NumberUtils.toInt(
                    tmpValue.trim(), VAL_DEF_PROMETHEUS_HTTP_PORT);
        }
        // read whether retry send message after sent failure
        tmpValue = compatGetValue(this.props,
                KEY_ENABLE_SEND_RETRY_AFTER_FAILUREV2, KEY_ENABLE_SEND_RETRY_AFTER_FAILURE);
        if (StringUtils.isNotEmpty(tmpValue)) {
            this.sendRetryAfterFailure = "TRUE".equalsIgnoreCase(tmpValue.trim());
        }
        // read max retry count
        tmpValue = compatGetValue(this.props,
                KEY_MAX_RETRIES_AFTER_FAILUREV2, KEY_MAX_RETRIES_AFTER_FAILURE);
        if (StringUtils.isNotBlank(tmpValue)) {
            int retries = NumberUtils.toInt(
                    tmpValue.trim(), VAL_DEF_MAX_RETRIES_AFTER_FAILURE);
            if (retries >= 0) {
                this.maxRetriesAfterFailure = retries;
            }
        }
        // Pre-read the fields related to Audit
        this.preReadAuditSetting();
        // Pre-read the fields related to File metric
        this.preReadMetricSetting();
        // pre-read v1msg default setting
        this.preReadV1MsgSetting();
    }
getStringFromContext

@param context
@param key
@param defaultValue
@return
inlong-dataproxy/dataproxy-source/src/main/java/org/apache/inlong/dataproxy/config/CommonConfigHolder.java