* consistency, and because the return type conveys the immutability guarantee.
   *
   * <p><b>Performance note:</b> the instance returned is a singleton.
   */
  @SuppressWarnings({"unchecked"}) // fully variant implementation (never actually produces any Es)
  public static <E> ImmutableSet<E> of() {
    return (ImmutableSet<E>) RegularImmutableSet.EMPTY;
  }

  /**

    /* nothing */
  }

  /**
   * This Iterator claims to have more elements than the underlying iterable, but when you try to
   * fetch the extra elements, it throws an unchecked exception.
   */
  static class ThrowsAtEndIterator<E> implements Iterator<E> {
    Iterator<E> iterator;

    public ThrowsAtEndIterator(Iterable<E> iterable) {
      this.iterator = iterable.iterator();

    // for use calling Collection.toArray later
    T[] emptyArray = Platform.newArray(strictlyOrderedElements, 0);

    // shoot me, but I didn't want to deal with wildcards through the whole test
    @SuppressWarnings("unchecked")
    Scenario<T> starter = new Scenario<>((Ordering<T>) ordering, list, emptyArray);
    verifyScenario(starter, 0);
  }

    // for use calling Collection.toArray later
    T[] emptyArray = Platform.newArray(strictlyOrderedElements, 0);

    // shoot me, but I didn't want to deal with wildcards through the whole test
    @SuppressWarnings("unchecked")
    Scenario<T> starter = new Scenario<>((Ordering<T>) ordering, list, emptyArray);
    verifyScenario(starter, 0);
  }

  /**
   * Returns the empty bimap.
   *
   * <p><b>Performance note:</b> the instance returned is a singleton.
   */
  // Casting to any type is safe because the set will never hold any elements.
  @SuppressWarnings("unchecked")
  public static <K, V> ImmutableBiMap<K, V> of() {
    return (ImmutableBiMap<K, V>) RegularImmutableBiMap.EMPTY;
  }

  /** Returns an immutable bimap containing a single entry. */

    @CheckForNull
    public Collection<V> get(@CheckForNull Object key) {
      Collection<V> result = unfiltered.asMap().get(key);
      if (result == null) {
        return null;
      }
      @SuppressWarnings("unchecked") // key is equal to a K, if not a K itself
      K k = (K) key;
      result = filterCollection(result, new ValuePredicate(k));
      return result.isEmpty() ? null : result;
    }

    @Override

    ReferenceEntry<Object, Object> entry = segment.getEntry(one, hash);
    ReferenceEntry<Object, Object> newEntry = segment.copyEntry(entry, null);
    table.set(index, newEntry);

    @SuppressWarnings("unchecked")
    LoadingValueReference<Object, Object> valueReference =
        (LoadingValueReference) newEntry.getValueReference();
    assertFalse(valueReference.futureValue.isDone());
    startSignal.countDown();

    ReferenceEntry<Object, Object> entry = segment.getEntry(one, hash);
    ReferenceEntry<Object, Object> newEntry = segment.copyEntry(entry, null);
    table.set(index, newEntry);

    @SuppressWarnings("unchecked")
    LoadingValueReference<Object, Object> valueReference =
        (LoadingValueReference) newEntry.getValueReference();
    assertFalse(valueReference.futureValue.isDone());
    startSignal.countDown();

    stream.writeObject(valueComparator());
    Serialization.writeMultimap(this, stream);
  }

  @GwtIncompatible // java.io.ObjectInputStream
  @J2ktIncompatible
  @SuppressWarnings("unchecked") // reading data stored by writeObject
  private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
    stream.defaultReadObject();

      throw new UnsupportedOperationException();
    }

    @SuppressWarnings("unchecked")
    @Override
    public boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
      return get((K) key).remove(value);
    }

    @SuppressWarnings("unchecked")
    @Override
    public Collection<V2> removeAll(@CheckForNull Object key) {