public Builder watermarkStrategy(WatermarkStrategy<RowData> watermarkStrategy) {
      if (watermarkStrategy != null) {
        this.watermarkStrategy = watermarkStrategy;
      }
      return this;
    }
An util class create mixed-format source data stream.
amoro-format-mixed/amoro-mixed-flink/amoro-mixed-flink-common/src/main/java/org/apache/amoro/flink/table/FlinkSource.java