* cells.
       */
      cellRowIndices[i] = requireNonNull(rowIndex.get(rowKey));
      Map<C, V> thisRow = requireNonNull(rows.get(rowKey));
      cellColumnInRowIndices[i] = thisRow.size();
      V oldValue = thisRow.put(columnKey, value);
      checkNoDuplicate(rowKey, columnKey, oldValue, value);
      requireNonNull(columns.get(columnKey)).put(rowKey, value);
    }
    this.cellRowIndices = cellRowIndices;

       * cells.
       */
      cellRowIndices[i] = requireNonNull(rowIndex.get(rowKey));
      Map<C, V> thisRow = requireNonNull(rows.get(rowKey));
      cellColumnInRowIndices[i] = thisRow.size();
      V oldValue = thisRow.put(columnKey, value);
      checkNoDuplicate(rowKey, columnKey, oldValue, value);
      requireNonNull(columns.get(columnKey)).put(rowKey, value);
    }
    this.cellRowIndices = cellRowIndices;

      values[rowIndex][columnIndex] = cell.getValue();
      rowCounts[rowIndex]++;
      columnCounts[columnIndex]++;
      cellRowIndices[i] = rowIndex;
      cellColumnIndices[i] = columnIndex;
    }
    this.cellRowIndices = cellRowIndices;
    this.cellColumnIndices = cellColumnIndices;
    this.rowMap = new RowMap();
    this.columnMap = new ColumnMap();
  }