/** 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}
   *

  ConcurrentMap<String, AtomicInteger> backingMap;
  ConcurrentHashMultiset<String> multiset;

  @SuppressWarnings("unchecked")
  @Override
  protected void setUp() {
    backingMap = mock(ConcurrentMap.class);
    when(backingMap.isEmpty()).thenReturn(true);

    multiset = ConcurrentHashMultiset.create(backingMap);
  }

  public void testCount_elementPresent() {

    checkArgument(backingMap.isEmpty());
    checkNotNull(factory);
    // TODO(jlevy): Wrap factory to validate that the supplied maps are empty?
    return new StandardTable<>(backingMap, factory);
  }

  /**
   * Returns a view of a table where each value is transformed by a function. All other properties
   * of the table, such as iteration order, are left intact.
   *

      // The Eclipse compiler (and hence GWT) rejects a parameterized cast.
      @SuppressWarnings("unchecked")
      LinkedHashMultimap<String, Integer>.ValueSet valueSet =
          (LinkedHashMultimap.ValueSet) multimap.backingMap().get("a");
      assertEquals(z, valueSet.size());
      assertFalse(
          Hashing.needsResizing(
              valueSet.size(),
              valueSet.hashTable.length,

      // The Eclipse compiler (and hence GWT) rejects a parameterized cast.
      @SuppressWarnings("unchecked")
      LinkedHashMultimap<String, Integer>.ValueSet valueSet =
          (LinkedHashMultimap.ValueSet) multimap.backingMap().get("a");
      assertEquals(z, valueSet.size());
      assertFalse(
          Hashing.needsResizing(
              valueSet.size(),
              valueSet.hashTable.length,

   * @return an empty collection of values
   */
  Collection<V> createCollection(@ParametricNullness K key) {
    return createCollection();
  }

  Map<K, Collection<V>> backingMap() {
    return map;
  }

  // Query Operations

  @Override
  public int size() {
    return totalSize;
  }

  @Override
  public boolean containsKey(@Nullable Object key) {