Iterable<Cell<R, C, V>> cells,
      @CheckForNull Comparator<? super R> rowComparator,
      @CheckForNull Comparator<? super C> columnComparator) {
    Set<R> rowSpaceBuilder = new LinkedHashSet<>();
    Set<C> columnSpaceBuilder = new LinkedHashSet<>();
    ImmutableList<Cell<R, C, V>> cellList = ImmutableList.copyOf(cells);
    for (Cell<R, C, V> cell : cells) {
      rowSpaceBuilder.add(cell.getRowKey());

        checkNotNull(cell.getRowKey(), "row");
        checkNotNull(cell.getColumnKey(), "column");
        checkNotNull(cell.getValue(), "value");
        @SuppressWarnings("unchecked") // all supported methods are covariant
        Cell<R, C, V> immutableCell = (Cell<R, C, V>) cell;
        cells.add(immutableCell);
      } else {
        put(cell.getRowKey(), cell.getColumnKey(), cell.getValue());
      }

   * the second row key, and so on.
   *
   * <p>The value in the returned cells may change if the table subsequently changes.
   *
   * @return set of table cells consisting of row key / column key / value triplets
   */
  @Override
  public Set<Cell<R, C, @Nullable V>> cellSet() {
    return super.cellSet();
  }

  @Override
  Iterator<Cell<R, C, @Nullable V>> cellIterator() {

    }

    @Override
    public Set<Cell<String, Integer, Character>> create(Object... elements) {
      Table<String, Integer, Character> table = createTable();
      for (Object element : elements) {
        @SuppressWarnings("unchecked")
        Cell<String, Integer, Character> cell = (Cell<String, Integer, Character>) element;
        table.put(cell.getRowKey(), cell.getColumnKey(), cell.getValue());
      }

    }

    @Override
    public Set<Cell<String, Integer, Character>> create(Object... elements) {
      Table<String, Integer, Character> table = createTable();
      for (Object element : elements) {
        @SuppressWarnings("unchecked")
        Cell<String, Integer, Character> cell = (Cell<String, Integer, Character>) element;
        table.put(cell.getRowKey(), cell.getColumnKey(), cell.getValue());
      }

  // This gives minimal coverage to the forwarding functions
  public void testToImmutableTableSanityTest() {
    Collector<Cell<String, String, Integer>, ?, ImmutableTable<String, String, Integer>> collector =
        toImmutableTable(Cell::getRowKey, Cell::getColumnKey, Cell::getValue);
    CollectorTester.of(collector)
        .expectCollects(ImmutableTable.of())

    public Map<R, V> column(@ParametricNullness C columnKey) {
      synchronized (mutex) {
        return map(delegate().column(columnKey), mutex);
      }
    }

    @Override
    public Set<Cell<R, C, V>> cellSet() {
      synchronized (mutex) {
        return set(delegate().cellSet(), mutex);
      }
    }

    @Override
    public Set<R> rowKeySet() {
      synchronized (mutex) {

    public Map<R, V> column(@ParametricNullness C columnKey) {
      synchronized (mutex) {
        return map(delegate().column(columnKey), mutex);
      }
    }

    @Override
    public Set<Cell<R, C, V>> cellSet() {
      synchronized (mutex) {
        return set(delegate().cellSet(), mutex);
      }
    }

    @Override
    public Set<R> rowKeySet() {
      synchronized (mutex) {