*       ordered pair of keys, a row key and column key.
 *   <dt>{@link Multiset}
 *   <dd>An extension of {@link java.util.Collection} that may contain duplicate values like a
 *       {@link java.util.List}, yet has order-independent equality like a {@link java.util.Set}.
 *       One typical use for a multiset is to represent a histogram.
 *   <dt>{@link ClassToInstanceMap}

import com.google.common.annotations.VisibleForTesting;
import com.google.common.primitives.Ints;
import java.util.Comparator;
import org.jspecify.annotations.Nullable;

/**
 * An immutable sorted multiset with one or more distinct elements.
 *
 * @author Louis Wasserman
 */
@SuppressWarnings("serial") // uses writeReplace, not default serialization
@GwtIncompatible

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests conditional {@code setCount()} operations on a multiset. Can't
 * be invoked directly; please see {@link MultisetTestSuiteBuilder}.
 *
 * @author Chris Povirk
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")

    Multiset<String> multiset = HashMultiset.create(50);
    multiset.add("foo", 2);
    multiset.add("bar");
    assertEquals(3, multiset.size());
    assertEquals(2, multiset.count("foo"));
  }

  public void testCreateFromIterable() {
    Multiset<String> multiset = HashMultiset.create(asList("foo", "bar", "foo"));
    assertEquals(3, multiset.size());
    assertEquals(2, multiset.count("foo"));
  }

  @J2ktIncompatible

  }

  @Override
  Map<K, Collection<V>> createAsMap() {
    return Maps.filterKeys(unfiltered.asMap(), keyPredicate);
  }

  @Override
  Multiset<K> createKeys() {
    return Multisets.filter(unfiltered.keys(), keyPredicate);
  }

  }

  @Override
  Map<K, Collection<V>> createAsMap() {
    return Maps.filterKeys(unfiltered.asMap(), keyPredicate);
  }

  @Override
  Multiset<K> createKeys() {
    return Multisets.filter(unfiltered.keys(), keyPredicate);
  }

   *
   * @param multiset the presumed-immutable multiset
   * @param sampleElement an element of the same type as that contained by {@code multiset}. {@code
   *     multiset} may or may not have {@code sampleElement} as a member.
   */
  public static <E extends @Nullable Object> void assertMultisetIsUnmodifiable(
      Multiset<E> multiset, E sampleElement) {
    Multiset<E> copy = LinkedHashMultiset.create(multiset);

  /**
   * Returns a view of this multiset restricted to the elements greater than {@code lowerBound},
   * optionally including {@code lowerBound} itself. The returned multiset is a view of this
   * multiset, so changes to one will be reflected in the other. The returned multiset supports all
   * operations that this multiset supports.
   *
   * <p>The returned multiset will throw an {@link IllegalArgumentException} on attempts to add

  /**
   * Returns a view of this multiset restricted to the elements greater than {@code lowerBound},
   * optionally including {@code lowerBound} itself. The returned multiset is a view of this
   * multiset, so changes to one will be reflected in the other. The returned multiset supports all
   * operations that this multiset supports.
   *
   * <p>The returned multiset will throw an {@link IllegalArgumentException} on attempts to add

@GwtCompatible
public enum MultisetFeature implements Feature<Multiset> {
  /**
   * Indicates that elements from {@code Multiset.entrySet()} update to reflect changes in the
   * backing multiset.
   */
  ENTRIES_ARE_VIEWS;

  @Override
  public Set<Feature<? super Multiset>> getImpliedFeatures() {
    return emptySet();
  }

  @Retention(RetentionPolicy.RUNTIME)
  @Inherited