public InLongMsg getInLongMsg() {
        InLongMsg message = InLongMsg.newInLongMsg(true);
        String attr = MessageUtils.convertAttrToStr(extraMap).toString();
        for (byte[] lineData : dataList) {
            message.addMsg(attr, lineData);
        }
        return message;
    }
A batch of proxy messages used for batch sending, produced by PackProxyMessage
inlong-agent/agent-common/src/main/java/org/apache/inlong/agent/message/file/SenderMessage.java