* an element in the set. For example, {@code contains} returns {@code false} when passed an
   * object that equals a set member, but isn't the same instance. This behavior is similar to the
   * way {@code IdentityHashMap} handles key lookups.
   *
   * @since 8.0
   */
  public static <E extends @Nullable Object> Set<E> newIdentityHashSet() {
    return Collections.newSetFromMap(Maps.<E, Boolean>newIdentityHashMap());
  }

/**
 * A general-purpose bimap implementation using any two backing {@code Map} instances.
 *
 * <p>Note that this class contains {@code equals()} calls that keep it from supporting {@code
 * IdentityHashMap} backing maps.
 *
 * @author Kevin Bourrillion
 * @author Mike Bostock
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault

            CollectionFeature.SERIALIZABLE,
            CollectionSize.ANY)
        .suppressing(suppressForConcurrentSkipListMap())
        .createTestSuite();
  }

  // TODO: IdentityHashMap, AbstractMap

  private static Map<String, String> toHashMap(Entry<String, String>[] entries) {
    return populate(new HashMap<String, String>(), entries);
  }

            CollectionFeature.SERIALIZABLE,
            CollectionSize.ANY)
        .suppressing(suppressForConcurrentSkipListMap())
        .createTestSuite();
  }

  // TODO: IdentityHashMap, AbstractMap

  private static Map<String, String> toHashMap(Entry<String, String>[] entries) {
    return populate(new HashMap<String, String>(), entries);
  }

/**
 * A general-purpose bimap implementation using any two backing {@code Map} instances.
 *
 * <p>Note that this class contains {@code equals()} calls that keep it from supporting {@code
 * IdentityHashMap} backing maps.
 *
 * @author Kevin Bourrillion
 * @author Mike Bostock
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault

    HashMap<Object, Object> map = Maps.<Object, Object>newLinkedHashMap(original);
    assertEquals(original, map);
  }

  // Intentionally using IdentityHashMap to test creation.
  @SuppressWarnings("IdentityHashMapBoxing")
  public void testIdentityHashMap() {
    IdentityHashMap<Integer, Integer> map = Maps.newIdentityHashMap();
    assertEquals(Collections.emptyMap(), map);
  }

  public void testConcurrentMap() {

    HashMap<Object, Object> map = Maps.<Object, Object>newLinkedHashMap(original);
    assertEquals(original, map);
  }

  // Intentionally using IdentityHashMap to test creation.
  @SuppressWarnings("IdentityHashMapBoxing")
  public void testIdentityHashMap() {
    IdentityHashMap<Integer, Integer> map = Maps.newIdentityHashMap();
    assertEquals(Collections.emptyMap(), map);
  }

  public void testConcurrentMap() {

import com.google.j2objc.annotations.J2ObjCIncompatible;
import java.lang.ref.SoftReference;
import java.lang.ref.WeakReference;
import java.util.ConcurrentModificationException;
import java.util.IdentityHashMap;
import java.util.Map;
import java.util.concurrent.TimeUnit;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.annotation.CheckForNull;

/**

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.lang.ref.SoftReference;
import java.lang.ref.WeakReference;
import java.util.ConcurrentModificationException;
import java.util.IdentityHashMap;
import java.util.Map;
import java.util.concurrent.TimeUnit;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.annotation.CheckForNull;

/**

  }

  /**
   * Creates an {@code IdentityHashMap} instance.
   *
   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
   * use the {@code IdentityHashMap} constructor directly, taking advantage of <a
   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
   *
   * @return a new, empty {@code IdentityHashMap}
   */