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

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

 *       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

    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.

  }

  /**
   * Returns an immutable map containing the given entries, in order.
   *
   * @throws IllegalArgumentException if duplicate keys are provided
   */
  public static <K, V> ImmutableMap<K, V> of(K k1, V v1, K k2, V v2) {
    return RegularImmutableMap.fromEntries(entryOf(k1, v1), entryOf(k2, v2));
  }

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

  }

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

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

  }

  /** 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. */

 * {@link ImmutableCollection}.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
 *
 * @author Jesse Wilson
 * @author Kevin Bourrillion
 * @since 2.0
 */
@DoNotMock("Use ImmutableMap.of or another implementation")
@GwtCompatible

/** Returns an immutable wrap of this. */
@Suppress("NOTHING_TO_INLINE")
internal inline fun <T> List<T>.unmodifiable(): List<T> = Collections.unmodifiableList(this)

/** Returns an immutable wrap of this. */
@Suppress("NOTHING_TO_INLINE")
internal inline fun <T> Set<T>.unmodifiable(): Set<T> = Collections.unmodifiableSet(this)

/** Returns an immutable wrap of this. */
@Suppress("NOTHING_TO_INLINE")

  }

  /**
   * Returns the empty immutable sorted set.
   *
   * <p><b>Performance note:</b> the instance returned is a singleton.
   */
  @SuppressWarnings("unchecked") // The natural-ordered empty set supports all types.
  public static <E> ImmutableSortedSet<E> of() {
    return (ImmutableSortedSet<E>) RegularImmutableSortedSet.NATURAL_EMPTY_SET;
  }

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