* ListMultimap} and {@link SetMultimap}. These take their names from the fact that the collections
 * they return from {@code get} behave like (and, of course, implement) {@link List} and {@link
 * Set}, respectively.
 *
 * <p>For example, the "presidents" code snippet above used a {@code ListMultimap}; if it had used a
 * {@code SetMultimap} instead, two presidents would have vanished, and last names might or might

  Collection<V> unmodifiableEmptyCollection() {
    // These return false, rather than throwing a UOE, on remove calls.
    return (unfiltered instanceof SetMultimap) ? emptySet() : emptyList();
  }

  @Override
  public void clear() {
    entries().clear();
  }

  @Override
  public Collection<V> get(@ParametricNullness K key) {

import java.util.stream.Collector;
import java.util.stream.Stream;
import org.jspecify.annotations.Nullable;

/**
 * A {@link SetMultimap} whose contents will never change, with many other important properties
 * detailed at {@link ImmutableCollection}.
 *
 * <p><b>Warning:</b> As in all {@link SetMultimap}s, do not modify either a key <i>or a value</i>
 * of a {@code ImmutableSetMultimap} in a way that affects its {@link Object#equals} behavior.

   * in the same order. If the value orderings disagree, the multimaps will not be considered equal.
   *
   * <p>An empty {@code ListMultimap} is equal to any other empty {@code Multimap}, including an
   * empty {@code SetMultimap}.
   */
  @Override
  boolean equals(@Nullable Object obj);

   * in the same order. If the value orderings disagree, the multimaps will not be considered equal.
   *
   * <p>An empty {@code ListMultimap} is equal to any other empty {@code Multimap}, including an
   * empty {@code SetMultimap}.
   */
  @Override
  boolean equals(@Nullable Object obj);

  @MapFeature.Require(SUPPORTS_REMOVE)
  /*
   * We are comparing Multimaps of the same type, so as long as they have value collections that
   * implement equals() (as with ListMultimap or SetMultimap, as opposed to a QueueMultimap or
   * something), our equality check is value-based.
   */
  @SuppressWarnings("UndefinedEquals")
  public void testRetainAllPropagatesToMultimap() {

import java.util.stream.Collector;
import java.util.stream.Stream;
import org.jspecify.annotations.Nullable;

/**
 * A {@link SetMultimap} whose contents will never change, with many other important properties
 * detailed at {@link ImmutableCollection}.
 *
 * <p><b>Warning:</b> As in all {@link SetMultimap}s, do not modify either a key <i>or a value</i>
 * of a {@code ImmutableSetMultimap} in a way that affects its {@link Object#equals} behavior.

      extends SynchronizedMultimap<K, V> implements SetMultimap<K, V> {
    transient @Nullable Set<Map.Entry<K, V>> entrySet;

    SynchronizedSetMultimap(SetMultimap<K, V> delegate, @Nullable Object mutex) {
      super(delegate, mutex);
    }

    @Override
    SetMultimap<K, V> delegate() {
      return (SetMultimap<K, V>) super.delegate();
    }

    @Override

  @MapFeature.Require(SUPPORTS_REMOVE)
  /*
   * We are comparing Multimaps of the same type, so as long as they have value collections that
   * implement equals() (as with ListMultimap or SetMultimap, as opposed to a QueueMultimap or
   * something), our equality check is value-based.
   */
  @SuppressWarnings("UndefinedEquals")
  public void testRetainAllPropagatesToMultimap() {

      extends SynchronizedMultimap<K, V> implements SetMultimap<K, V> {
    transient @Nullable Set<Map.Entry<K, V>> entrySet;

    SynchronizedSetMultimap(SetMultimap<K, V> delegate, @Nullable Object mutex) {
      super(delegate, mutex);
    }

    @Override
    SetMultimap<K, V> delegate() {
      return (SetMultimap<K, V>) super.delegate();
    }

    @Override