private void loadTableIfNeeded() {
      if (tableLoader == null || mixedTable != null) {
        return;
      }
      mixedTable = MixedFormatUtils.loadMixedTable(tableLoader);
      properties.putAll(mixedTable.properties());
    }
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