@Override
  protected final void assertMoreInvariants(Map<K, V> map) {
    BiMap<K, V> bimap = (BiMap<K, V>) map;

    for (Entry<K, V> entry : map.entrySet()) {
      assertEquals(entry.getKey() + "=" + entry.getValue(), entry.toString());
      assertEquals(entry.getKey(), bimap.inverse().get(entry.getValue()));
    }

    assertEquals("{" + JOINER.join(map.entrySet()) + "}", map.toString());

      super(backward, forward);
    }

    /*
     * Serialization stores the forward bimap, the inverse of this inverse.
     * Deserialization calls inverse() on the forward bimap and returns that
     * inverse.
     *
     * If a bimap and its inverse are serialized together, the deserialized
     * instances have inverse() methods that return the other.
     */

  }

  static <K extends @Nullable Object, V extends @Nullable Object> BiMap<K, V> biMap(
      BiMap<K, V> bimap, @CheckForNull Object mutex) {
    if (bimap instanceof SynchronizedBiMap || bimap instanceof ImmutableBiMap) {
      return bimap;
    }
    return new SynchronizedBiMap<>(bimap, mutex, null);
  }

package com.google.common.collect;

import com.google.common.annotations.GwtCompatible;

@GwtCompatible
@ElementTypesAreNonnullByDefault
public class FilteredBiMapTest extends AbstractFilteredMapTest {
  @Override
  BiMap<String, Integer> createUnfiltered() {
    return HashBiMap.create();
  }

 *   <dt>{@link BiMap}
 *   <dd>An extension of {@link java.util.Map} that guarantees the uniqueness of its values as well
 *       as that of its keys. This is sometimes called an "invertible map," since the restriction on
 *       values enables it to support an {@linkplain BiMap#inverse inverse view} -- which is another
 *       instance of {@code BiMap}.
 *   <dt>{@link Table}

  public void testSetMultimap() {
    assertFreshInstance(new TypeToken<SetMultimap<String, ?>>() {});
  }

  public void testBiMap() {
    assertFreshInstance(new TypeToken<BiMap<String, ?>>() {});
    assertNotInstantiable(new TypeToken<BiMap<EmptyEnum, String>>() {});
  }

  public void testHashBiMap() {
    assertFreshInstance(new TypeToken<HashBiMap<String, ?>>() {});
  }

  public void testTable() {

package com.google.common.collect;

import com.google.common.annotations.GwtCompatible;

@GwtCompatible
@ElementTypesAreNonnullByDefault
public class FilteredBiMapTest extends AbstractFilteredMapTest {
  @Override
  BiMap<String, Integer> createUnfiltered() {
    return HashBiMap.create();
  }

  public void testSetMultimap() {
    assertFreshInstance(new TypeToken<SetMultimap<String, ?>>() {});
  }

  public void testBiMap() {
    assertFreshInstance(new TypeToken<BiMap<String, ?>>() {});
    assertNotInstantiable(new TypeToken<BiMap<EmptyEnum, String>>() {});
  }

  public void testHashBiMap() {
    assertFreshInstance(new TypeToken<HashBiMap<String, ?>>() {});
  }

  public void testTable() {

    if (map instanceof ImmutableBiMap) {
      @SuppressWarnings("unchecked") // safe since map is not writable
      ImmutableBiMap<K, V> bimap = (ImmutableBiMap<K, V>) map;
      return bimap;
    }

    if (map.isEmpty()) {
      return of();
    }

    ImmutableMap<K, V> immutableMap = ImmutableMap.copyOf(map);

import com.google.common.annotations.J2ktIncompatible;
import com.google.common.annotations.VisibleForTesting;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Bimap with zero or more mappings.
 *
 * @author Louis Wasserman
 */
@GwtCompatible(serializable = true, emulated = true)
@SuppressWarnings("serial") // uses writeReplace(), not default serialization