TableCollectors.toImmutableTable(Cell::getRowKey, Cell::getColumnKey, t -> null);
    try {
      Stream.of(immutableCell("one", "uno", 1)).collect(collector);
      fail("Expected NullPointerException");
    } catch (NullPointerException expected) {
    }
    collector =
        TableCollectors.toImmutableTable(Cell::getRowKey, Cell::getColumnKey, Cell::getValue);
    try {

                      @SuppressWarnings("unchecked")
                      Cell<String, Integer, Character> cell =
                          (Cell<String, Integer, Character>) element;
                      table.put(cell.getRowKey(), cell.getColumnKey(), cell.getValue());
                    }
                    return table.cellSet();
                  }

                  @Override

                      @SuppressWarnings("unchecked")
                      Cell<String, Integer, Character> cell =
                          (Cell<String, Integer, Character>) element;
                      table.put(cell.getRowKey(), cell.getColumnKey(), cell.getValue());
                    }
                    return table.cellSet();
                  }

                  @Override

        Cell<?, ?, ?> other = (Cell<?, ?, ?>) obj;
        return Objects.equal(getRowKey(), other.getRowKey())
            && Objects.equal(getColumnKey(), other.getColumnKey())
            && Objects.equal(getValue(), other.getValue());
      }
      return false;
    }

    @Override
    public int hashCode() {
      return Objects.hashCode(getRowKey(), getColumnKey(), getValue());
    }

    @Override

        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());
      }

  public void testToImmutableTableSanityTest() {
    Collector<Cell<String, String, Integer>, ?, ImmutableTable<String, String, Integer>> collector =
        TableCollectors.toImmutableTable(Cell::getRowKey, Cell::getColumnKey, Cell::getValue);
    CollectorTester.of(collector)
        .expectCollects(ImmutableTable.of())
        .expectCollects(ImmutableTable.of("one", "uno", 1), Tables.immutableCell("one", "uno", 1));
  }

   * @since 7.0
   */
  interface Cell<
      R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object> {
    /** Returns the row key of this cell. */
    @ParametricNullness
    R getRowKey();

    /** Returns the column key of this cell. */
    @ParametricNullness
    C getColumnKey();

    /** Returns the value of this cell. */
    @ParametricNullness
    V getValue();

    /**

        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());
      }

    int[] cellRowIndices = new int[cellList.size()];
    int[] cellColumnIndices = new int[cellList.size()];
    for (int i = 0; i < cellList.size(); i++) {
      Cell<R, C, V> cell = cellList.get(i);
      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));

  }

  public void testHashing() throws Exception {
    for (String stringToTest : INPUTS) {
      for (Table.Cell<String, SecretKey, HashFunction> cell : ALGORITHMS.cellSet()) {
        String algorithm = cell.getRowKey();
        SecretKey key = cell.getColumnKey();
        HashFunction hashFunc = cell.getValue();
        assertMacHashing(HashTestUtils.ascii(stringToTest), algorithm, key, hashFunc);
      }
    }
  }