@Override
  public T next() {
    updateCurrentIterator();
    recordOffset += 1;
    T row = currentIterator.next();
    currentFileOffset = fileOffsetGetter.apply(row);
    return metaColumnRemover.apply(row);
  }
(startingFileOffset, startingRecordOffset) points to the next row that the reader should resume
from. E.g., if the seek position is (file=0, record=1), seek moves the iterator position to the
second row in file 0. When next() is called after seek; the second row from file 0 should be
returned.
amoro-format-mixed/amoro-mixed-flink/amoro-mixed-flink-common/src/main/java/org/apache/amoro/flink/read/source/DataIterator.java