immutableCell(null, null, null);
    assertThat(nullEntry.toString()).isEqualTo("(null,null)=null");
  }

  public void testEntryEquals() {
    Cell<String, Integer, Character> entry = immutableCell("foo", 1, 'a');

    new EqualsTester()
        .addEqualityGroup(entry, immutableCell("foo", 1, 'a'))
        .addEqualityGroup(immutableCell("bar", 1, 'a'))
        .addEqualityGroup(immutableCell("foo", 2, 'a'))

        immutableCell(null, null, null);
    assertThat(nullEntry.toString()).isEqualTo("(null,null)=null");
  }

  public void testEntryEquals() {
    Cell<String, Integer, Character> entry = immutableCell("foo", 1, 'a');

    new EqualsTester()
        .addEqualityGroup(entry, immutableCell("foo", 1, 'a'))
        .addEqualityGroup(immutableCell("bar", 1, 'a'))
        .addEqualityGroup(immutableCell("foo", 2, 'a'))

@NullMarked
public class RegularImmutableTableTest extends AbstractImmutableTableTest {
  private static final ImmutableSet<Cell<Character, Integer, String>> CELLS =
      ImmutableSet.of(
          immutableCell('a', 1, "foo"), immutableCell('b', 1, "bar"), immutableCell('a', 2, "baz"));

  private static final ImmutableSet<Character> ROW_SPACE = ImmutableSet.of('a', 'b');

  private static final ImmutableSet<Integer> COLUMN_SPACE = ImmutableSet.of(1, 2);

                    return new SampleElements<>(
                        immutableCell("bar", 1, 'a'),
                        immutableCell("bar", 2, 'b'),
                        immutableCell("bar", 3, (Character) null),
                        immutableCell("bar", 4, 'b'),
                        immutableCell("bar", 5, 'b'));
                  }

                  @Override

                    return new SampleElements<>(
                        immutableCell("bar", 1, 'a'),
                        immutableCell("bar", 2, 'b'),
                        immutableCell("bar", 3, (Character) null),
                        immutableCell("bar", 4, 'b'),
                        immutableCell("bar", 5, 'b'));
                  }

                  @Override

    CollectorTester.of(collector)
        .expectCollects(ImmutableTable.of())
        .expectCollects(
            ImmutableTable.of("one", "uno", 3),
            immutableCell("one", "uno", 1),
            immutableCell("one", "uno", 2));
  }

  public void testBuilder() {
    ImmutableTable.Builder<Character, Integer, String> builder = new ImmutableTable.Builder<>();

      Cell<R, C, V> immutableCell(
          @ParametricNullness R rowKey,
          @ParametricNullness C columnKey,
          @ParametricNullness V value) {
    return new ImmutableCell<>(rowKey, columnKey, value);
  }

  static final class ImmutableCell<
          R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>

      Cell<R, C, V> immutableCell(
          @ParametricNullness R rowKey,
          @ParametricNullness C columnKey,
          @ParametricNullness V value) {
    return new ImmutableCell<>(rowKey, columnKey, value);
  }

  static final class ImmutableCell<
          R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>

      if (cell instanceof Tables.ImmutableCell) {
        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 {

      if (cell instanceof Tables.ImmutableCell) {
        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 {