private Struct signalRecordValue(String splitId, WatermarkKind watermarkKind) {
        Struct result = new Struct(signalEventValueSchema);
        result.put(SPLIT_ID_KEY, splitId);
        result.put(WATERMARK_KIND, watermarkKind.toString());
        return result;
    }
A dispatcher to dispatch watermark signal events.

<p>The watermark signal event is used to describe the start point and end point of a split scan.
The Watermark Signal Algorithm is inspired by https://arxiv.org/pdf/2010.12597v1.pdf.</p>
inlong-sort/sort-flink/sort-flink-v1.13/sort-connectors/mysql-cdc/src/main/java/org/apache/inlong/sort/cdc/mysql/debezium/dispatcher/SignalEventDispatcher.java