private static Struct signalRecordValue(String splitId, WatermarkKind watermarkKind) {
        Struct result = new Struct(SIGNAL_EVENT_VALUE_SCHEMA);
        result.put(SPLIT_ID_KEY, splitId);
        result.put(WATERMARK_KIND, watermarkKind.toString());
        return result;
    }
Utility class to deal Watermark event.
Copy from com.ververica:flink-cdc-base:2.3.0.
inlong-sort/sort-flink/cdc-base/src/main/java/org/apache/inlong/sort/cdc/base/source/meta/wartermark/WatermarkEvent.java