@Override
    protected InLongMsgHead parseHead(String attr) throws Exception {
        return InLongMsgTlogKvUtils.parseHead(attr);
    }
The literal represented null values, default "".
inlong-sort/sort-formats/format-rowdata/format-inlongmsg-rowdata-tlogkv/src/main/java/org/apache/inlong/sort/formats/inlongmsgtlogkv/InLongMsgTlogKvFormatDeserializer.java