@Override
  public void processWatermark(Watermark mark) throws Exception {
    if (logWriter != null) {
      logWriter.processWatermark(mark);
    }
    if (fileWriter instanceof Input) {
      ((Input) fileWriter).processWatermark(mark);
    }
    super.processWatermark(mark);
  }
This is the general entry of an mixed-format writer that wraps different operators insides.

@param <OUT>
amoro-format-mixed/amoro-mixed-flink/amoro-mixed-flink-common/src/main/java/org/apache/amoro/flink/write/MixedFormatWriter.java