return (ImmutableBiMap<K, V>) RegularImmutableBiMap.EMPTY;
  }

  /** Returns an immutable bimap containing a single entry. */
  public static <K, V> ImmutableBiMap<K, V> of(K k1, V v1) {
    checkEntryNotNull(k1, v1);
    return new RegularImmutableBiMap<>(new Object[] {k1, v1}, 1);
  }

  /**
   * Returns an immutable map containing the given entries, in order.
   *

  private static final Collector<Object, ?, ImmutableList<Object>> TO_IMMUTABLE_LIST =
      Collector.of(
          ImmutableList::builder,
          ImmutableList.Builder::add,
          ImmutableList.Builder::combine,
          ImmutableList.Builder::build);

  private static final Collector<Object, ?, ImmutableSet<Object>> TO_IMMUTABLE_SET =
      Collector.of(
          ImmutableSet::builder,

     */
    @Nonnull
    Optional<Path> getPath(Project project);

    /**
     * Returns an immutable collection of attached artifacts for given project.
     */
    @Nonnull
    Collection<Artifact> getAttachedArtifacts(Project project);

    /**
     * Returns project's all artifacts as immutable collection. The list contains all artifacts, even the attached ones,

  }

  /**
   * Returns an immutable collection of the values for the given key. If no mappings in the multimap
   * have the provided key, an empty immutable collection is returned. The values are in the same
   * order as the parameters used to build this multimap.
   */
  @Override
  public abstract ImmutableCollection<V> get(K key);

  /**

    // If add is supported, verify that IMMUTABLE is not reported.
    synchronized (collection) { // for Collections.synchronized
      assertFalse(collection.spliterator().hasCharacteristics(Spliterator.IMMUTABLE));
    }
  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  public void testSpliteratorNotImmutable_CollectionAllowsRemove() {
    // If remove is supported, verify that IMMUTABLE is not reported.

    return new SingletonImmutableList<>(element);
  }

  /**
   * Returns an immutable list containing the given elements, in order.
   *
   * @throws NullPointerException if any element is null
   */
  public static <E> ImmutableList<E> of(E e1, E e2) {
    return construct(e1, e2);
  }

  /**
   * Returns an immutable list containing the given elements, in order.
   *

 *       mutable objects as elements at all, as many users may expect your "immutable" object to be
 *       <i>deeply</i> immutable.
 * </ul>
 *
 * <h4>Performance notes</h4>
 *
 * <ul>
 *   <li>Implementations can be generally assumed to prioritize memory efficiency, then speed of
 *       access, and lastly speed of creation.
 *   <li>The {@code copyOf} methods will sometimes recognize that the actual copy operation is

  }

  /** Returns an immutable multimap containing a single entry. */
  public static <K, V> ImmutableListMultimap<K, V> of(K k1, V v1) {
    ImmutableListMultimap.Builder<K, V> builder = ImmutableListMultimap.builder();
    builder.put(k1, v1);
    return builder.build();
  }

  /** Returns an immutable multimap containing the given entries, in order. */

  }

  /**
   * Returns the empty immutable sorted multiset.
   *
   * <p><b>Performance note:</b> the instance returned is a singleton.
   */
  @SuppressWarnings("unchecked")
  public static <E> ImmutableSortedMultiset<E> of() {
    return (ImmutableSortedMultiset) RegularImmutableSortedMultiset.NATURAL_EMPTY_MULTISET;
  }

  /** Returns an immutable sorted multiset containing a single element. */

    if (actualIterator.hasNext()) {
      fail("index " + i + ", expected is exhausted, actual <" + actualIterator.next() + ">");
    }
  }

  /**
   * Verifies that a collection is immutable.
   *
   * <p>A collection is considered immutable if:
   *
   * <ol>
   *   <li>All its mutation methods result in UnsupportedOperationException, and do not change the
   *       underlying contents.