private static Optional<SignalEventDispatcher.WatermarkKind> getWatermarkKind(SourceRecord record) {
        if (record.valueSchema() != null
                && SIGNAL_EVENT_VALUE_SCHEMA_NAME.equals(record.valueSchema().name())) {
            Struct value = (Struct) record.value();
            return Optional.of(SignalEventDispatcher.WatermarkKind.valueOf(value.getString(WATERMARK_KIND)));
        }
        return Optional.empty();
    }
Returns a split which contain the specific key.

@param splitInfos split info list.
@param target the specific key.
@return A split which contain the specific key.
inlong-sort/sort-flink/sort-flink-v1.13/sort-connectors/mysql-cdc/src/main/java/org/apache/inlong/sort/cdc/mysql/source/utils/RecordUtils.java