import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import java.lang.ref.PhantomReference;
import java.lang.ref.ReferenceQueue;
import org.jspecify.annotations.Nullable;

/**
 * Phantom reference with a {@code finalizeReferent()} method which a background thread invokes
 * after the garbage collector reclaims the referent. This is a simpler alternative to using a
 * {@link ReferenceQueue}.

import java.lang.ref.ReferenceQueue;
import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.jspecify.annotations.Nullable;

/**
 * A reference queue with an associated background thread that dequeues references and invokes
 * {@link FinalizableReference#finalizeReferent()} on them. Java 9+ users should prefer {@link

    } catch (UnsupportedOperationException e) {
      return;
    }

    map.put(null, unmappedValue);
    Entry<@Nullable K, V> entry = mapEntry(null, unmappedValue);
    assertTrue(entrySet.contains(entry));
    Entry<@Nullable K, @Nullable V> nonEntry = mapEntry(null, null);
    assertFalse(entrySet.contains(nonEntry));
  }

  public void testEntrySetContainsEntryNullKeyMissing() {

import com.google.common.annotations.J2ktIncompatible;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.Serializable;
import java.util.Map.Entry;
import org.jspecify.annotations.Nullable;

/**
 * {@code entrySet()} implementation for {@link ImmutableMap}.
 *
 * @author Jesse Wilson
 * @author Kevin Bourrillion
 */
@GwtCompatible

  @CanIgnoreReturnValue // pushed down from class to method
  @Override
  public @Nullable E poll() {
    Monitor monitor = this.monitor;
    monitor.enter();
    try {
      return q.poll();
    } finally {
      monitor.leave();
    }
  }

  @CanIgnoreReturnValue // pushed down from class to method
  @Override
  public @Nullable E poll(long timeout, TimeUnit unit) throws InterruptedException {

import java.lang.ref.WeakReference;
import java.util.Iterator;
import java.util.NoSuchElementException;
import junit.framework.TestCase;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * Unit test for {@code AbstractIterator}.
 *
 * @author Kevin Bourrillion
 */
@SuppressWarnings("serial") // No serialization is used in this test
@GwtCompatible
@NullMarked

import java.lang.ref.WeakReference;
import java.util.Iterator;
import java.util.NoSuchElementException;
import junit.framework.TestCase;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * Unit test for {@code AbstractIterator}.
 *
 * @author Kevin Bourrillion
 */
@SuppressWarnings("serial") // No serialization is used in this test
@GwtCompatible
@NullMarked

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

/**
 * To be implemented by test generators that can produce test subjects without requiring any
 * parameters.
 *
 * @param <T> the type created by this generator.
 * @author George van den Driessche
 */
@GwtCompatible
@NullMarked
public interface TestSubjectGenerator<T extends @Nullable Object> {
  T createTestSubject();

        public Map<String, String> userProperties;
        public Path topDirectory;

        @Nullable
        public Path rootDirectory;

        @Nullable
        public List<CoreExtensions> extensions;

        @Nullable
        public CIInfo ciInfo;

        @Nullable
        public Options options;

        public Map<String, String> extraInterpolationSource() {

import static java.util.Collections.singletonMap;

import org.jspecify.annotations.Nullable;

/**
 * GWT emulation of {@link SingletonImmutableBiMap}.
 *
 * @author Hayward Chan
 */
final class SingletonImmutableBiMap<K, V> extends ImmutableBiMap<K, V> {
  private final K singleKey;
  private final V singleValue;

  @Nullable transient SingletonImmutableBiMap<V, K> inverse;

  SingletonImmutableBiMap(K key, V value) {