private GenericAppenderHelper appender() {
    return new GenericAppenderHelper(table, fileFormat, tmp, conf);
  }
Appends the rows to the table. If the table is partitioned then it will create the correct partitions.
@param rowSet The rows to add
@throws IOException If there is an exception during writing out the files
iceberg/iceberg-handler/src/test/java/org/apache/iceberg/mr/TestHelper.java