this.cellColumnIndices = cellColumnIndices;
    }

    static SerializedForm create(
        ImmutableTable<?, ?, ?> table, int[] cellRowIndices, int[] cellColumnIndices) {
      return new SerializedForm(
          table.rowKeySet().toArray(),
          table.columnKeySet().toArray(),
          table.values().toArray(),
          cellRowIndices,
          cellColumnIndices);
    }

      this.cellColumnIndices = cellColumnIndices;
    }

    static SerializedForm create(
        ImmutableTable<?, ?, ?> table, int[] cellRowIndices, int[] cellColumnIndices) {
      return new SerializedForm(
          table.rowKeySet().toArray(),
          table.columnKeySet().toArray(),
          table.values().toArray(),
          cellRowIndices,
          cellColumnIndices);
    }

    int[] cellColumnIndices = new int[cellSet().size()];
    int i = 0;
    for (Cell<R, C, V> cell : cellSet()) {
      // requireNonNull is safe because the cell exists in the table.
      cellColumnIndices[i++] = requireNonNull(columnKeyToIndex.get(cell.getColumnKey()));
    }
    return SerializedForm.create(this, cellRowIndices, cellColumnIndices);
  }