BiMap<K, V> synchronizedBiMap(BiMap<K, V> bimap) {
    return Synchronized.biMap(bimap, null);
  }

  /**
   * Returns an unmodifiable view of the specified bimap. This method allows modules to provide
   * users with "read-only" access to internal bimaps. Query operations on the returned bimap "read
   * through" to the specified bimap, and attempts to modify the returned map, whether direct or via