public static UnkeyedTable baseStore(MixedTable mixedTable) {
    if (mixedTable.isKeyedTable()) {
      return mixedTable.asKeyedTable().baseTable();
    } else {
      return mixedTable.asUnkeyedTable();
    }
  }
Return the base store of the mixed-format table.
amoro-format-iceberg/src/main/java/org/apache/amoro/utils/MixedTableUtil.java