*/
  @Override
  public ImmutableSet<V> get(K key) {
    // This cast is safe as its type is known in constructor.
    ImmutableSet<V> set = (ImmutableSet<V>) map.get(key);
    return MoreObjects.firstNonNull(set, emptySet);
  }

  @LazyInit @RetainedWith private transient @Nullable ImmutableSetMultimap<V, K> inverse;

  /**
   * {@inheritDoc}
   *

      L existing = locks.get(index);
      if (existing != null) {
        return existing;
      }
      L created = supplier.get();
      existing = locks.putIfAbsent(index, created);
      return MoreObjects.firstNonNull(existing, created);
    }

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

  /** A bit mask were all bits are set. */
  private static final int ALL_SET = ~0;

   */
  @Override
  public ImmutableSet<V> get(K key) {
    // This cast is safe as its type is known in constructor.
    ImmutableSet<V> set = (ImmutableSet<V>) map.get(key);
    return MoreObjects.firstNonNull(set, emptySet);
  }

  @LazyInit @RetainedWith private transient @Nullable ImmutableSetMultimap<V, K> inverse;

  /**
   * {@inheritDoc}
   *

      return existing;
    }
    Map<E, LockGraphNode> created = createNodes(clazz);
    existing = (Map<E, LockGraphNode>) lockGraphNodesPerType.putIfAbsent(clazz, created);
    return MoreObjects.firstNonNull(existing, created);
  }

  /**
   * For a given Enum type, creates an immutable map from each of the Enum's values to a
   * corresponding LockGraphNode, with the {@code allowedPriorLocks} and {@code