protected void sanityCheckLeft(byte[] left, Cell cell) throws IOException {
    if (
      !Arrays.equals(StripeStoreFileManager.OPEN_KEY, left)
        && comparator.compareRows(cell, left, 0, left.length) < 0
    ) {
      String error =
        "The first row is lower than the left boundary of [" + Bytes.toString(left) + "]: ["
          + Bytes.toString(cell.getRowArray(), cell.getRowOffset(), cell.getRowLength()) + "]";
      LOG.error(error);
      throw new IOException(error);
    }
  }
Subclasses can call this method to make sure the first KV is within multi-writer range.
@param left The left boundary of the writer.
@param cell The cell whose row has to be checked.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/StripeMultiFileWriter.java