return new OldConcurrentHashMultiset<E>(new ConcurrentHashMap<E, Integer>());
    }

    @VisibleForTesting
    OldConcurrentHashMultiset(ConcurrentMap<E, Integer> countMap) {
      checkArgument(countMap.isEmpty());
      this.countMap = countMap;
    }

    // Query Operations

    /**
     * Returns the number of occurrences of {@code element} in this multiset.
     *