public static boolean isWatermarkEvent(SourceRecord record) {
        Optional<WatermarkKind> watermarkKind = getWatermarkKind(record);
        return watermarkKind.isPresent();
    }
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