public String getScn() {
        return offset.get(SCN_KEY);
    }
A structure describes an offset in a redo log event.
 Copy from com.ververica:flink-connector-oracle-cdc:2.3.0
inlong-sort/sort-flink/sort-flink-v1.13/sort-connectors/oracle-cdc/src/main/java/org/apache/inlong/sort/cdc/oracle/source/meta/offset/RedoLogOffset.java