@Override
  public void enforceSeek() throws IOException {
    throw new NotImplementedException("enforceSeek cannot be called on a SegmentScanner");
  }
This function should be never called on scanners that always do real seek operations (i.e. most
of the scanners and also this one). The easiest way to achieve this is to call
{@link #realSeekDone()} first.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/SegmentScanner.java