@Override
    public T next() {
      T next = currentIterator.next();
      GenericRecord rec = (GenericRecord) next;
      return recordBuilder.withSpecId(partitionSpec.specId())
          .withPartitionHash(computeHash(partition))
          .withFilePath(IcebergAcidUtil.getFilePath(rec))
          .withFilePosition(IcebergAcidUtil.getDeleteFilePosition(rec))
          .withPartitionKey(getSerializedPartitionKey(partition, partitionSpec)).build();
    }
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