/** Standard constructor. */
  protected AbstractMapBasedMultiset(Map<E, Count> backingMap) {
    checkArgument(backingMap.isEmpty());
    this.backingMap = backingMap;
  }

  /** Used during deserialization only. The backing map must be empty. */
  void setBackingMap(Map<E, Count> backingMap) {
    this.backingMap = backingMap;
  }

  // Required Implementations

  /**
   * {@inheritDoc}
   *

import java.util.Set;
import org.jspecify.annotations.Nullable;

/**
 * A map which forwards all its method calls to another map. Subclasses should override one or more
 * methods to modify the behavior of the backing map as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingMap} forward <i>indiscriminately</i> to the

import org.jspecify.annotations.Nullable;

/**
 * A sorted multiset which forwards all its method calls to another sorted multiset. Subclasses
 * should override one or more methods to modify the behavior of the backing multiset as desired per
 * the <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingSortedMultiset} forward

   */
  public long sum() {
    return map.values().stream().mapToLong(Long::longValue).sum();
  }

  @LazyInit private transient @Nullable Map<K, Long> asMap;

  /** Returns a live, read-only view of the map backing this {@code AtomicLongMap}. */
  public Map<K, Long> asMap() {
    Map<K, Long> result = asMap;
    return (result == null) ? asMap = createAsMap() : result;
  }

  private Map<K, Long> createAsMap() {

      }
    }

    // can't use Serialization writeMultimap and populateMultimap methods since
    // there's no way to generate the empty backing map.

    /**
     * @serialData the factory and the backing map
     */
    @GwtIncompatible
    @J2ktIncompatible
        private void writeObject(ObjectOutputStream stream) throws IOException {
      stream.defaultWriteObject();

import org.jspecify.annotations.Nullable;

/**
 * A navigable map which forwards all its method calls to another navigable map. Subclasses should
 * override one or more methods to modify the behavior of the backing map as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingNavigableMap} forward <i>indiscriminately</i>

import org.jspecify.annotations.Nullable;

/**
 * A navigable map which forwards all its method calls to another navigable map. Subclasses should
 * override one or more methods to modify the behavior of the backing map as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingNavigableMap} forward <i>indiscriminately</i>

        new SetSupplier() {
          @Override
          public Set<Integer> getImpl() {
            Set<Integer> backing = super.getImpl();
            return new ForwardingSet<Integer>() {
              @Override
              protected Set<Integer> delegate() {
                return backing;
              }

              @Override
              public boolean add(Integer element) {

import java.util.Set;
import org.jspecify.annotations.Nullable;

/**
 * A multiset which forwards all its method calls to another multiset. Subclasses should override
 * one or more methods to modify the behavior of the backing multiset as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingMultiset} forward <b>indiscriminately</b> to

      this.original = original;
    }

    /*
     * These gymnastics are a little confusing. Basically this class has neither legacy nor
     * non-legacy behavior; it just needs to let the behavior of the backing converter shine
     * through. So, we override the correctedDo* methods, after which the do* methods should never
     * be reached.
     */

    @Override
    protected A doForward(B b) {