private void extractStreamFromMessage(Message message, byte[] fieldSplitter) {
        if (messageFilter != null) {
            message.getHeader().put(CommonConstants.PROXY_KEY_STREAM_ID,
                    messageFilter.filterStreamId(message, fieldSplitter));
        }
    }
extract stream id from message if message filter is presented
inlong-agent/agent-plugins/src/main/java/org/apache/inlong/agent/plugin/sinks/ProxySink.java