/**
 * An implementation of {@link ImmutableTable} that holds a single cell.
 *
 * @author Gregory Kick
 */
@GwtCompatible
final class SingletonImmutableTable<R, C, V> extends ImmutableTable<R, C, V> {
  final R singleRowKey;
  final C singleColumnKey;
  final V singleValue;

  SingletonImmutableTable(R rowKey, C columnKey, V value) {
    this.singleRowKey = checkNotNull(rowKey);
    this.singleColumnKey = checkNotNull(columnKey);

import java.util.Objects;
import org.jspecify.annotations.NullMarked;

/**
 * Tests {@link SingletonImmutableTable}.
 *
 * @author Gregory Kick
 */
@GwtCompatible
@NullMarked
public class SingletonImmutableTableTest extends AbstractImmutableTableTest {
  private final ImmutableTable<Character, Integer, String> testTable =
      new SingletonImmutableTable<>('a', 1, "blah");

  public void testHashCode() {