*
   * <p>A non-empty {@link SetMultimap} cannot be equal to a non-empty {@link ListMultimap}, since
   * their {@link #asMap} views contain unequal collections as values. However, any two empty
   * multimaps are equal, because they both have empty {@link #asMap} views.
   */
  @Override
  boolean equals(@Nullable Object obj);

  /**
   * Returns the hash code for this multimap.
   *

 *
 * <p>Collection-returning accessors return unmodifiable views: the view returned will reflect
 * changes to the graph (if the graph is mutable) but may not be modified by the user.
 *
 * <p>The time complexity of all collection-returning accessors is O(1), since views are returned.
 *
 * @author James Sexton
 * @author Joshua O'Madadhain
 * @author Omar Darwish

 *
 * <p>Collection-returning accessors return unmodifiable views: the view returned will reflect
 * changes to the graph (if the graph is mutable) but may not be modified by the user.
 *
 * <p>The time complexity of all collection-returning accessors is O(1), since views are returned.
 *
 * @author James Sexton
 * @author Joshua O'Madadhain
 * @author Omar Darwish

   * {@code factory.get()} does.
   *
   * <p>Call this method only when the simpler factory methods in classes like {@link
   * HashBasedTable} and {@link TreeBasedTable} won't suffice.
   *
   * <p>The views returned by the {@code Table} methods {@link Table#column}, {@link
   * Table#columnKeySet}, and {@link Table#columnMap} have iterators that don't support {@code

   *     map entries may have been added to the bimap before the exception was thrown.
   */
  @Override
  void putAll(Map<? extends K, ? extends V> map);

  // Views

  /**
   * {@inheritDoc}
   *
   * <p>Because a bimap has unique values, this method returns a {@link Set}, instead of the {@link
   * java.util.Collection} specified in the {@link Map} interface.
   */

 * #entries()}, and {@link #asMap()} return collections that are views of the multimap. If the
 * multimap is modified while an iteration over any of those collections is in progress, except
 * through the iterator's methods, the results of the iteration are undefined.
 *
 * <p>Keys and values may be null. All optional multimap methods are supported, and all returned
 * views are modifiable.
 *

  @Override
  public final boolean retainAll(Collection<?> elementsToRetain) {
    return Multisets.retainAllImpl(this, elementsToRetain);
  }

  @Override
  public abstract void clear();

  // Views

  @LazyInit private transient @Nullable Set<E> elementSet;

  @Override
  public Set<E> elementSet() {
    Set<E> result = elementSet;
    if (result == null) {

      TestSortedSetGenerator<E> delegate, Bound to, Bound from) {
    return using(new NavigableSetSubsetTestSetGenerator<E>(delegate, to, from));
  }

  /** Create a suite whose maps are descending views of other maps. */
  private TestSuite createDescendingSuite(
      FeatureSpecificTestSuiteBuilder<?, ? extends OneSizeTestContainerGenerator<Collection<E>, E>>
          parentBuilder) {
    TestSetGenerator<E> delegate =

   * correct, but not that they're actually forwarding correctly. We also rely
   * on the other tests (e.g., SynchronizedSetTest) to verify that the
   * collection views are synchronized correctly.
   */

  public void testSize() {
    int unused = create().size();
  }

  public void testIsEmpty() {
    boolean unused = create().isEmpty();
  }

 * secondary maps. This class provides rapid access to records by the row key alone or by both keys,
 * but not by just the column key.
 *
 * <p>The views returned by {@link #column}, {@link #columnKeySet()}, and {@link #columnMap()} have
 * iterators that don't support {@code remove()}. Otherwise, all optional operations are supported.