Integer value = getOnlyElement(entry.getValue());
        builder.put(entry.getKey(), value);
      }
      return builder.buildOrThrow().asMultimap().asMap();
    }

    @Override
    @SuppressWarnings({"unchecked", "rawtypes"}) // needed for arrays
    public Entry<String, Collection<Integer>>[] createArray(int length) {
      return new Entry[length];
    }

 *   <li>No stats are modified when a cache entry is invalidated or manually removed.
 *   <li>No stats are modified by operations invoked on the {@linkplain Cache#asMap asMap} view of
 *       the cache.
 * </ul>
 *
 * <p>A lookup is specifically defined as an invocation of one of the methods {@link
 * LoadingCache#get(Object)}, {@link LoadingCache#getUnchecked(Object)}, {@link Cache#get(Object,

 *   <li>No stats are modified when a cache entry is invalidated or manually removed.
 *   <li>No stats are modified by operations invoked on the {@linkplain Cache#asMap asMap} view of
 *       the cache.
 * </ul>
 *
 * <p>A lookup is specifically defined as an invocation of one of the methods {@link
 * LoadingCache#get(Object)}, {@link LoadingCache#getUnchecked(Object)}, {@link Cache#get(Object,

    assertThrows(IllegalStateException.class, () -> builder.removalListener(testListener));
  }

  @J2ktIncompatible // asMap
  public void testValuesIsNotASet() {
    assertThat(CacheBuilder.newBuilder().build().asMap().values() instanceof Set).isFalse();
  }

  @J2ktIncompatible
  @GwtIncompatible // CacheTesting
  public void testNullCache() {

   * created, it is undefined which of the changes (if any) will be reflected in that iterator.
   */
  @J2ktIncompatible // Thread safety complexity
  ConcurrentMap<K, V> asMap();

  /**
   * Performs any pending maintenance operations needed by the cache. Exactly which activities are
   * performed -- if any -- is implementation-dependent.
   */
  void cleanUp();

        }
        return entries;
      }
    }

    @Override
    public Map<K, Collection<V>> asMap() {
      synchronized (mutex) {
        if (asMap == null) {
          asMap = new SynchronizedAsMap<>(delegate().asMap(), mutex);
        }
        return asMap;
      }
    }

    @Override
    public Multiset<K> keys() {
      synchronized (mutex) {

 * {@link #replaceValues} attempts to preserve iteration order as much as possible.
 *
 * <p>The collections returned by {@link #keySet()} and {@link #asMap()} iterate through the keys in
 * the order they were first added to the multimap. Similarly, {@link #get}, {@link #removeAll}, and
 * {@link #replaceValues} return collections that iterate through the values in the order they were

    throw new UnsupportedOperationException();
  }

  @Override
  public CacheStats stats() {
    throw new UnsupportedOperationException();
  }

  @Override
  public ConcurrentMap<K, V> asMap() {
    throw new UnsupportedOperationException();
  }

  /**
   * Accumulates statistics during the operation of a {@link Cache} for presentation by {@link

        delegate().forEach(action);
      }
    }

    @Override
    public Map<K, Collection<V>> asMap() {
      synchronized (mutex) {
        if (asMap == null) {
          asMap = new SynchronizedAsMap<>(delegate().asMap(), mutex);
        }
        return asMap;
      }
    }

    @Override
    public Multiset<K> keys() {
      synchronized (mutex) {

 * {@link #replaceValues} attempts to preserve iteration order as much as possible.
 *
 * <p>The collections returned by {@link #keySet()} and {@link #asMap()} iterate through the keys in
 * the order they were first added to the multimap. Similarly, {@link #get}, {@link #removeAll}, and
 * {@link #replaceValues} return collections that iterate through the values in the order they were