return keyOrNull(floorEntry(key));
  }

  @Override
  @CheckForNull
  public Entry<K, V> ceilingEntry(K key) {
    return tailMap(key, true).firstEntry();
  }

  @Override
  @CheckForNull
  public K ceilingKey(K key) {
    return keyOrNull(ceilingEntry(key));
  }

  @Override
  @CheckForNull
  public Entry<K, V> higherEntry(K key) {

    @Override
    public boolean containsEntry(@CheckForNull Object key, @CheckForNull Object value) {
      synchronized (mutex) {
        return delegate().containsEntry(key, value);
      }
    }

    @Override
    public Collection<V> get(@ParametricNullness K key) {
      synchronized (mutex) {
        return typePreservingCollection(delegate().get(key), mutex);
      }
    }

    @Override

  E getEntry(@CheckForNull Object key) {
    if (key == null) {
      return null;
    }
    int hash = hash(key);
    return segmentFor(hash).getEntry(key, hash);
  }

  @Override
  public boolean containsKey(@CheckForNull Object key) {
    if (key == null) {
      return false;
    }
    int hash = hash(key);
    return segmentFor(hash).containsKey(key, hash);
  }

  @Override

    @Override
    @CheckForNull
    public Collection<V> get(@CheckForNull Object key) {
      return containsKey(key) ? multimap.get((K) key) : null;
    }

    @Override
    @CheckForNull
    public Collection<V> remove(@CheckForNull Object key) {
      return containsKey(key) ? multimap.removeAll(key) : null;
    }

    @Override
    public Set<K> keySet() {

   * 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());
  }

  /**

  /**
   * If a hostname is not a key in the EXCLUDE map, and if removing its leftmost component results
   * in a name which is a key in this map, it is a public suffix.
   */
  public static final ImmutableMap<String, PublicSuffixType> UNDER =
      TrieParser.parseTrie(