abstract class AbstractMultimap<K extends @Nullable Object, V extends @Nullable Object>
    implements Multimap<K, V> {
  @Override
  public boolean isEmpty() {
    return size() == 0;
  }

  @Override
  public boolean containsValue(@CheckForNull Object value) {
    for (Collection<V> collection : asMap().values()) {
      if (collection.contains(value)) {
        return true;
      }
    }

    return false;
  }

  @Override

abstract class AbstractMultimap<K extends @Nullable Object, V extends @Nullable Object>
    implements Multimap<K, V> {
  @Override
  public boolean isEmpty() {
    return size() == 0;
  }

  @Override
  public boolean containsValue(@CheckForNull Object value) {
    for (Collection<V> collection : asMap().values()) {
      if (collection.contains(value)) {
        return true;
      }
    }

    return false;
  }

  @Override

      assertTrue(Thread.holdsLock(mutex));
      return super.containsKey(key);
    }

    @Override
    public boolean containsValue(@Nullable Object value) {
      assertTrue(Thread.holdsLock(mutex));
      return super.containsValue(value);
    }

    @Override
    public boolean containsEntry(@Nullable Object key, @Nullable Object value) {
      assertTrue(Thread.holdsLock(mutex));

    }

    @Override
    public boolean containsKey(final Object key) {
        return getProperties().containsKey(key);
    }

    @Override
    public boolean containsValue(final Object value) {
        return getProperties().containsValue(value);
    }

    @Override
    public Enumeration<Object> elements() {
        return getProperties().elements();
    }

    @Override

  }

  @Override
  public Iterator<V> iterator() {
    return Maps.valueIterator(multimap.entries().iterator());
  }

  @Override
  public boolean contains(@CheckForNull Object o) {
    return multimap.containsValue(o);
  }

  @Override
  public int size() {
    return multimap.size();
  }

  @Override
  public boolean remove(@CheckForNull Object o) {

      assertTrue(Thread.holdsLock(mutex));
      return super.containsKey(key);
    }

    @Override
    public boolean containsValue(@Nullable Object value) {
      assertTrue(Thread.holdsLock(mutex));
      return super.containsValue(value);
    }

    @Override
    public boolean containsEntry(@Nullable Object key, @Nullable Object value) {
      assertTrue(Thread.holdsLock(mutex));

      return delegate.containsKey(checkValid(key));
    } catch (NullPointerException | ClassCastException e) {
      return false;
    }
  }

  @Override
  public boolean containsValue(Object value) {
    return delegate.containsValue(value);
  }

  @Override
  public NavigableSet<K> descendingKeySet() {
    return delegate.descendingKeySet();
  }

  @Override

      return delegate.containsKey(checkValid(key));
    } catch (NullPointerException | ClassCastException e) {
      return false;
    }
  }

  @Override
  public boolean containsValue(Object value) {
    return delegate.containsValue(value);
  }

  @Override
  public NavigableSet<K> descendingKeySet() {
    return delegate.descendingKeySet();
  }

  @Override

    }
  }

  protected void expectMissingValues(V... elements) {
    for (V element : elements) {
      assertFalse("Should not contain value " + element, getMap().containsValue(element));
    }
  }

  /** @return an array of the proper size with {@code null} as the key of the middle element. */
  protected Entry<K, V>[] createArrayWithNullKey() {

   */
  ALLOWS_NULL_KEY_QUERIES,
  ALLOWS_NULL_KEYS(ALLOWS_NULL_KEY_QUERIES),
  /**
   * The map does not throw {@code NullPointerException} on calls such as {@code
   * containsValue(null)}, {@code values().contains(null)} or {@code values().remove(null)}.
   */
  ALLOWS_NULL_VALUE_QUERIES,
  ALLOWS_NULL_VALUES(ALLOWS_NULL_VALUE_QUERIES),
  /**