* @since 2.0
 */
@GwtCompatible
public abstract class ForwardingConcurrentMap<K, V> extends ForwardingMap<K, V>
    implements ConcurrentMap<K, V> {

  /** Constructor for use by subclasses. */
  protected ForwardingConcurrentMap() {}

  @Override
  protected abstract ConcurrentMap<K, V> delegate();

  @CanIgnoreReturnValue
  @Override
  public @Nullable V putIfAbsent(K key, V value) {

import com.google.common.collect.testing.features.CollectionSize;
import com.google.common.collect.testing.features.MapFeature;
import java.util.concurrent.ConcurrentMap;
import org.jspecify.annotations.NullMarked;
import org.junit.Ignore;

/**
 * Tester for {@link ConcurrentMap#remove}. Can't be invoked directly; please see {@link
 * com.google.common.collect.testing.ConcurrentMapTestSuiteBuilder}.
 *
 * @author Louis Wasserman
 */

@SuppressWarnings("JUnit4ClassUsedInJUnit3")
@NullMarked
public class ConcurrentMapPutIfAbsentTester<K, V> extends AbstractMapTester<K, V> {
  @Override
  protected ConcurrentMap<K, V> getMap() {
    return (ConcurrentMap<K, V>) super.getMap();
  }

  @MapFeature.Require(SUPPORTS_PUT)
  public void testPutIfAbsent_supportedAbsent() {

@SuppressWarnings("JUnit4ClassUsedInJUnit3")
@NullMarked
public class ConcurrentMapReplaceEntryTester<K, V> extends AbstractMapTester<K, V> {
  @Override
  protected ConcurrentMap<K, V> getMap() {
    return (ConcurrentMap<K, V>) super.getMap();
  }

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testReplaceEntry_supportedPresent() {

@SuppressWarnings("JUnit4ClassUsedInJUnit3")
@NullMarked
public class ConcurrentMapPutIfAbsentTester<K, V> extends AbstractMapTester<K, V> {
  @Override
  protected ConcurrentMap<K, V> getMap() {
    return (ConcurrentMap<K, V>) super.getMap();
  }

  @MapFeature.Require(SUPPORTS_PUT)
  public void testPutIfAbsent_supportedAbsent() {

import static com.google.common.base.Preconditions.checkArgument;

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

/**
 * MapMaker emulation.
 *
 * @author Charles Fry
 */
public final class MapMaker {
  private int initialCapacity = 16;

  public MapMaker() {}

  @CanIgnoreReturnValue

 * @since 2.0
 */
@GwtCompatible
public abstract class ForwardingConcurrentMap<K, V> extends ForwardingMap<K, V>
    implements ConcurrentMap<K, V> {

  /** Constructor for use by subclasses. */
  protected ForwardingConcurrentMap() {}

  @Override
  protected abstract ConcurrentMap<K, V> delegate();

  @CanIgnoreReturnValue
  @Override
  public @Nullable V putIfAbsent(K key, V value) {

  private static class TestMap extends ForwardingConcurrentMap<String, Integer> {
    final ConcurrentMap<String, Integer> delegate = new ConcurrentHashMap<>();

    @Override
    protected ConcurrentMap<String, Integer> delegate() {
      return delegate;
    }
  }

  public void testPutIfAbsent() {
    TestMap map = new TestMap();
    map.put("foo", 1);

@SuppressWarnings("JUnit4ClassUsedInJUnit3")
@NullMarked
public class ConcurrentMapReplaceTester<K, V> extends AbstractMapTester<K, V> {
  @Override
  protected ConcurrentMap<K, V> getMap() {
    return (ConcurrentMap<K, V>) super.getMap();
  }

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testReplace_supportedPresent() {

   * have been newly added to {@link ConcurrentMap}! These are marked with "Since: 1.8" in the
   * {@code ConcurrentMap} documentation. They will not function correctly and it is impossible for
   * Guava to fix them until Guava is ready to <i>require</i> Java 8 for all users.
   */
  ConcurrentMap<K, V> asMap();

  /**