import org.jspecify.annotations.Nullable;

/** Implementations of {@code Futures.transform*}. */
@GwtCompatible
// Whenever both tests are cheap and functional, it's faster to use &, | instead of &&, ||
@SuppressWarnings("ShortCircuitBoolean")
abstract class AbstractTransformFuture<
        I extends @Nullable Object, O extends @Nullable Object, F, T extends @Nullable Object>

   */

  @LazyInit private @Nullable ListenableFuture<V> delegateRef;
  @LazyInit private @Nullable ScheduledFuture<?> timer;

  private TimeoutFuture(ListenableFuture<V> delegate) {
    this.delegateRef = Preconditions.checkNotNull(delegate);
  }

  /** A runnable that is called when the delegate or the timer completes. */
  private static final class Fire<V extends @Nullable Object> implements Runnable {

    assertMultimapRemainsUnmodified(multimap, originalEntries);
  }

  private static <E extends @Nullable Object> void assertCollectionsAreEquivalent(
      Collection<E> expected, Collection<E> actual) {
    assertIteratorsInOrder(expected.iterator(), actual.iterator());
  }

  private static <K extends @Nullable Object, V extends @Nullable Object>
      void assertMultimapRemainsUnmodified(Multimap<K, V> expected, List<Entry<K, V>> actual) {

  }

  private static Iterable<@Nullable Object> iterable(
      @Nullable Object first, @Nullable Object second, @Nullable Object[] rest) {
    checkNotNull(rest);
    return new AbstractList<@Nullable Object>() {
      @Override
      public int size() {
        return rest.length + 2;
      }

      @Override
      public @Nullable Object get(int index) {
        switch (index) {

                mergeFunction),
        (s1, s2) -> s1.combine(s2, mergeFunction),
        state -> state.toTable());
  }

  static <
          T extends @Nullable Object,
          R extends @Nullable Object,
          C extends @Nullable Object,
          V,
          I extends Table<R, C, V>>
      Collector<T, ?, I> toTable(
          Function<? super T, ? extends R> rowFunction,

import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * Tests for {@link Functions}.
 *
 * @author Mike Bostock
 * @author Vlad Patryshev
 */
@GwtCompatible
@NullMarked
public class FunctionsTest extends TestCase {

  public void testIdentity_same() {
    Function<@Nullable String, @Nullable String> identity = Functions.identity();
    assertNull(identity.apply(null));

  static final RegularImmutableBiMap<Object, Object> EMPTY = new RegularImmutableBiMap<>();

  private final transient @Nullable Object keyHashTable;
  @VisibleForTesting final transient @Nullable Object[] alternatingKeysAndValues;
  private final transient int keyOffset; // 0 for K-to-V, 1 for V-to-K
  private final transient int size;
  private final transient RegularImmutableBiMap<V, K> inverse;

    this.forward = forward;
  }

  @Override
  public int count(@Nullable Object element) {
    return forward.count(element);
  }

  @Override
  public @Nullable Entry<E> firstEntry() {
    return forward.lastEntry();
  }

  @Override
  public @Nullable Entry<E> lastEntry() {
    return forward.firstEntry();
  }

  @Override
  public int size() {

   * there's no way to assign a {@code @Nullable T} to a field {@code T foo;} and instruct the
   * analysis that that means "plain {@code T}" rather than the inferred type {@code @Nullable T}.
   * (And even if annotations on local variables were permitted as an optional hint, no annotation
   * would be the right tool for the job here: {@code @Nullable} is the annotation that we're trying

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/**
 * Used to test listenable future implementations.
 *
 * @author Sven Mawson
 */
@NullUnmarked
public class ListenableFutureTester {

  private final ExecutorService exec;