}

  @CollectionSize.Require(ONE)
  @CollectionFeature.Require(SUPPORTS_REMOVE)
  public void testEntrySet_retainAllPresent() {
    assertFalse(
        "multiset.entrySet.retainAll(presentEntry) returned false",
        getMultiset().entrySet().retainAll(singleton(Multisets.immutableEntry(e0(), 1))));
    assertTrue(
        "multiset doesn't contains element after retaining its entry",
        getMultiset().contains(e0()));
  }

      assertTrue(Thread.holdsLock(mutex));
      return delegate.addAll(collection);
    }

    @Override
    public boolean retainAll(Collection<?> collection) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.retainAll(collection);
    }

    @Override
    public void clear() {
      assertTrue(Thread.holdsLock(mutex));
      delegate.clear();
    }

      }
      return changed;
    }

    @Override
    public boolean retainAll(Collection<?> c) {
      checkNotNull(c);
      boolean changed = false;
      Iterator<Map<C, V>> iterator = backingMap.values().iterator();
      while (iterator.hasNext()) {
        Map<C, V> map = iterator.next();
        if (map.keySet().retainAll(c)) {
          changed = true;
          if (map.isEmpty()) {

    return Multisets.removeAllImpl(this, elementsToRemove);
  }

  /**
   * A sensible definition of {@link #retainAll} in terms of the {@code retainAll} method of {@link
   * #elementSet}. If you override {@link #elementSet}, you may wish to override {@link #retainAll}
   * to forward to this implementation.
   *
   * @since 7.0
   */
  @Override

  }

  @CollectionSize.Require(ONE)
  @CollectionFeature.Require(SUPPORTS_REMOVE)
  public void testEntrySet_retainAllPresent() {
    assertFalse(
        "multiset.entrySet.retainAll(presentEntry) returned false",
        getMultiset().entrySet().retainAll(singleton(Multisets.immutableEntry(e0(), 1))));
    assertTrue(
        "multiset doesn't contains element after retaining its entry",
        getMultiset().contains(e0()));
  }

                  return map.entrySet().removeAll(c);
                }

                @Override
                public boolean retainAll(Collection<?> c) {
                  return map.entrySet().retainAll(c);
                }

                @Override
                public int hashCode() {
                  return map.entrySet().hashCode();
                }

    return Multisets.removeAllImpl(this, elementsToRemove);
  }

  /**
   * A sensible definition of {@link #retainAll} in terms of the {@code retainAll} method of {@link
   * #elementSet}. If you override {@link #elementSet}, you may wish to override {@link #retainAll}
   * to forward to this implementation.
   *
   * @since 7.0
   */
  @Override

  public boolean removeAll(Collection<?> c) {
    assertTrue(Thread.holdsLock(mutex));
    return super.removeAll(c);
  }

  @Override
  public boolean retainAll(Collection<?> c) {
    assertTrue(Thread.holdsLock(mutex));
    return super.retainAll(c);
  }

  @Override
  public int size() {
    assertTrue(Thread.holdsLock(mutex));
    return super.size();
  }

  @Override

  public boolean removeAll(Collection<?> c) {
    assertTrue(Thread.holdsLock(mutex));
    return super.removeAll(c);
  }

  @Override
  public boolean retainAll(Collection<?> c) {
    assertTrue(Thread.holdsLock(mutex));
    return super.retainAll(c);
  }

  @Override
  public int size() {
    assertTrue(Thread.holdsLock(mutex));
    return super.size();
  }

  @Override

    Multimap<String, Integer> filtered = filterValues(keyFiltered, VALUE_PREDICATE);
    assertEquals(1, filtered.size());
    assertTrue(filtered.containsEntry("foo", 1));
    assertTrue(filtered.keySet().retainAll(asList("cat", "dog")));
    assertEquals(0, filtered.size());
  }

  // TODO(jlevy): Many more tests needed.