Set<Object> keys = cache.asMap().keySet();
      assertFalse(keys.remove(null));
      assertFalse(keys.remove(6));
      assertFalse(keys.remove(-6));
      assertFalse(keys.removeAll(asList(null, 0, 15, 1500)));
      assertFalse(keys.retainAll(asList(null, 0, 15, 1500)));
      checkEmpty(keys);
      checkEmpty(cache);
    }
  }

  public void testKeySet_remove() {

      // invalidated and have undefined behavior after entrySet.removeAll(entriesToRemove),
      // for example entryToRemove.getValue() might be null.
      Entry<K, V> entryToRemoveCopy = mapEntry(entryToRemove.getKey(), entryToRemove.getValue());

      int initialSize = map.size();
      boolean didRemove = entrySet.removeAll(entriesToRemove);
      assertTrue(didRemove);

    } catch (UnsupportedOperationException expected) {
    }
    assertMultimapRemainsUnmodified(multimap, originalEntries);

    // Test #removeAll()
    try {
      multimap.removeAll(sampleKey);
      fail("removeAll succeeded on unmodifiable multimap");
    } catch (UnsupportedOperationException expected) {
    }
    assertMultimapRemainsUnmodified(multimap, originalEntries);

    }
  }

  @Override
  public boolean containsKey(@Nullable Object key) {
    return asMap().get(key) != null;
  }

  @Override
  public Collection<V> removeAll(@Nullable Object key) {
    return MoreObjects.firstNonNull(asMap().remove(key), unmodifiableEmptyCollection());
  }

  @SuppressWarnings("EmptyList") // ImmutableList doesn't support nullable element types

        public Iterator<K> iterator() {
          return Iterators.unmodifiableIterator(delegate.keySet().iterator());
        }

        @Override
        public boolean removeAll(Collection<?> c) {
          return delegate.keySet().removeAll(c);
        }

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

    }
  }

  @Override
  public boolean containsKey(@Nullable Object key) {
    return asMap().get(key) != null;
  }

  @Override
  public Collection<V> removeAll(@Nullable Object key) {
    return MoreObjects.firstNonNull(asMap().remove(key), unmodifiableEmptyCollection());
  }

  @SuppressWarnings("EmptyList") // ImmutableList doesn't support nullable element types

 *       the values corresponding to {@code key}
 * </ul>
 *
 * <p>The collections returned by the {@link #replaceValues replaceValues} and {@link #removeAll
 * removeAll} methods, which contain values that have just been removed from the multimap, are
 * naturally <i>not</i> views.
 *
 * <h3>Subinterfaces</h3>
 *

    return remove(element, 1) > 0;
  }

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

  }

  /**
   * Confirm that removeAll() returns a List that implements RandomAccess, even though get()
   * doesn't.
   */
  public void testRemoveAllRandomAccess() {
    Multimap<String, Integer> multimap = create();
    multimap.put("foo", 1);
    multimap.put("foo", 3);
    assertTrue(multimap.removeAll("foo") instanceof RandomAccess);
    assertTrue(multimap.removeAll("bar") instanceof RandomAccess);
  }

    }

    @Override
    public boolean remove(final Object o) {
        return parent.remove(o);
    }

    @Override
    public boolean removeAll(final Collection<?> c) {
        return parent.removeAll(c);
    }

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

    @Override