R rowKey = cell.getRowKey();
      C columnKey = cell.getColumnKey();
      // The requireNonNull calls are safe because we construct the indexes with indexMap.
      int rowIndex = requireNonNull(rowKeyToIndex.get(rowKey));
      int columnIndex = requireNonNull(columnKeyToIndex.get(columnKey));
      V existingValue = values[rowIndex][columnIndex];
      checkNoDuplicate(rowKey, columnKey, existingValue, cell.getValue());

      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;
    this.cellColumnInRowIndices = cellColumnInRowIndices;

      return (Table<R, C, V>) super.delegate();
    }

    @Override
    public boolean contains(@Nullable Object rowKey, @Nullable Object columnKey) {
      synchronized (mutex) {
        return delegate().contains(rowKey, columnKey);
      }
    }

    @Override
    public boolean containsRow(@Nullable Object rowKey) {
      synchronized (mutex) {

      return (Table<R, C, V>) super.delegate();
    }

    @Override
    public boolean contains(@Nullable Object rowKey, @Nullable Object columnKey) {
      synchronized (mutex) {
        return delegate().contains(rowKey, columnKey);
      }
    }

    @Override
    public boolean containsRow(@Nullable Object rowKey) {
      synchronized (mutex) {

    }

    public ColumnInfo columnKey() {
        return _columnKey;
    }

    public ColumnInfo columnValue() {
        return _columnValue;
    }

    protected List<ColumnInfo> ccil() {
        List<ColumnInfo> ls = newArrayList();
        ls.add(columnCrawlingInfoId());
        ls.add(columnCreatedTime());
        ls.add(columnKey());
        ls.add(columnValue());
        return ls;

   * referencing the type variables seem worthwhile.
   */
  final void checkNoDuplicate(R rowKey, C columnKey, @Nullable V existingValue, V newValue) {
    checkArgument(
        existingValue == null,
        "Duplicate key: (row=%s, column=%s), values: [%s, %s].",
        rowKey,
        columnKey,
        newValue,
        existingValue);
  }

  // redeclare to satisfy our test for b/310253115

 *
 * <p>Lookups by row key are often faster than lookups by column key, because the data is stored in
 * a {@code Map<R, Map<C, V>>}. A method call like {@code column(columnKey).get(rowKey)} still runs
 * quickly, since the row key is provided. However, {@code column(columnKey).size()} takes longer,
 * since an iteration across all row keys occurs.
 *
 * <p>Note that this implementation is not synchronized. If multiple threads access this table

 *
 * <p>Lookups by row key are often faster than lookups by column key, because the data is stored in
 * a {@code Map<R, Map<C, V>>}. A method call like {@code column(columnKey).get(rowKey)} still runs
 * quickly, since the row key is provided. However, {@code column(columnKey).size()} takes longer,
 * since an iteration across all row keys occurs.
 *
 * <p>Note that this implementation is not synchronized. If multiple threads access this table

   * referencing the type variables seem worthwhile.
   */
  final void checkNoDuplicate(R rowKey, C columnKey, @Nullable V existingValue, V newValue) {
    checkArgument(
        existingValue == null,
        "Duplicate key: (row=%s, column=%s), values: [%s, %s].",
        rowKey,
        columnKey,
        newValue,
        existingValue);
  }

  // redeclare to satisfy our test for b/310253115

 *
 * <p>Lookups by row key are often faster than lookups by column key, because the data is stored in
 * a {@code Map<R, Map<C, V>>}. A method call like {@code column(columnKey).get(rowKey)} still runs
 * quickly, since the row key is provided. However, {@code column(columnKey).size()} takes longer,
 * since an iteration across all row keys occurs.
 *
 * <p>Because a {@code TreeBasedTable} has unique sorted values for a given row, both {@code