public static int parseSpecId(Record rec) {
    return rec.get(FILE_READ_META_COLS.get(MetadataColumns.SPEC_ID), Integer.class);
  }
Get the new record from the updated record. Populate the `newRecord` with the filed values from `rec`.
@param rec The record read by the file scan task, which contains both the metadata fields and the row data fields
@param newRecord The record object to populate. The end result is the new record after the update.
iceberg/iceberg-handler/src/main/java/org/apache/iceberg/mr/hive/IcebergAcidUtil.java