List<? extends Entry<?, ?>> entries = Lists.newArrayList(map.entrySet());
    List<Object> keys = Lists.newArrayList(map.keySet());
    List<Object> values = Lists.newArrayList(map.values());
    assertEquals(2 * entries.size(), alternatingKeysAndValues.length);
    assertEquals(2 * keys.size(), alternatingKeysAndValues.length);
    assertEquals(2 * values.size(), alternatingKeysAndValues.length);

          map.put(element, element);
        }
        return map;
      }
    },
    UnmodHM {
      @Override
      Map<Element, Element> create(Collection<Element> keys) {
        return Collections.unmodifiableMap(Hash.create(keys));
      }
    },
    SyncHM {
      @Override
      Map<Element, Element> create(Collection<Element> keys) {
        return Collections.synchronizedMap(Hash.create(keys));
      }

  /**
   * Computes or retrieves the values corresponding to {@code keys}. This method is called by {@link
   * LoadingCache#getAll}.
   *
   * <p>If the returned map doesn't contain all requested {@code keys} then the entries it does
   * contain will be cached, but {@code getAll} will throw an exception. If the returned map
   * contains extra keys not present in {@code keys} then all returned entries will be cached, but

  /**
   * Returns a {@link Collector} that accumulates elements into an {@code ImmutableBiMap} whose keys
   * and values are the result of applying the provided mapping functions to the input elements.
   * Entries appear in the result {@code ImmutableBiMap} in encounter order.
   *
   * <p>If the mapped keys or values contain duplicates (according to {@link

                        keys ->
                            path.create(
                                Lists.transform(
                                    keys, key -> Maps.immutableEntry(key, new Object()))),
                        keys ->
                            path.create(
                                Lists.transform(
                                    keys, key -> Maps.immutableEntry(new Object(), key))),

        .withFeatures(
            MapFeature.GENERAL_PURPOSE,
            MapFeature.ALLOWS_NULL_KEYS,
            MapFeature.ALLOWS_NULL_VALUES,
            MapFeature.ALLOWS_ANY_NULL_QUERIES,
            MapFeature.FAILS_FAST_ON_CONCURRENT_MODIFICATION,
            MapFeature.RESTRICTS_KEYS,
            MapFeature.RESTRICTS_VALUES,
            CollectionFeature.SUPPORTS_ITERATOR_REMOVE,

    private final ImmutableList<String> keys;
    private final Random random = new Random();

    private MutateTask(ConcurrentHashMultiset<String> multiset, ImmutableList<String> keys) {
      this.multiset = multiset;
      this.keys = keys;
    }

    @Override
    public int[] call() throws Exception {
      int iterations = 100000;
      int nKeys = keys.size();
      int[] deltas = new int[nKeys];

  private static final int DEFAULT_EXPECTED_KEYS = 8;

  /** Uses a hash table to map keys to value collections. */
  public static MultimapBuilderWithKeys<@Nullable Object> hashKeys() {
    return hashKeys(DEFAULT_EXPECTED_KEYS);
  }

  /**
   * Uses a hash table to map keys to value collections, initialized to expect the specified number
   * of keys.
   *

          .addEqualityGroup(cache.asMap().keySet(), keys)
          .addEqualityGroup(ImmutableSet.of())
          .testEquals();
      assertEquals(WARMUP_SIZE, keys.size());
      for (int i = WARMUP_MIN; i < WARMUP_MAX; i++) {
        Object key = warmed.get(i - WARMUP_MIN).getKey();
        assertTrue(keys.contains(key));
        assertTrue(keys.remove(key));
        assertFalse(keys.remove(key));
        assertFalse(keys.contains(key));

  /**
   * Returns a {@link Collector} that accumulates elements into an {@code ImmutableBiMap} whose keys
   * and values are the result of applying the provided mapping functions to the input elements.
   * Entries appear in the result {@code ImmutableBiMap} in encounter order.
   *
   * <p>If the mapped keys or values contain duplicates (according to {@link