code: private List<Cell> checkEmptyRow(KV<ImmutableBytesWritable, Result> kv) {
      List<Cell> cells = kv.getValue().listCells();
      if (cells == null) {
        cells = Collections.emptyList();
      }
      if (!isEmptyRowWarned && cells.isEmpty()) {
        logger.warn("Encountered empty row. Was input file serialized by HBase 0.94?");
        isEmptyRowWarned = true;
      }
      return cells;
    }
docs: Warns about empty row on first occurrence only and replaces a null array with 0-length one.