};
  }

  /**
   * Returns a "nefarious" map entry with the specified key and value, meaning an entry that is
   * suitable for testing that map entries cannot be modified via a nefarious implementation of
   * equals. This is used for testing unmodifiable collections of map entries; for example, it
   * should not be possible to access the raw (modifiable) map entry via a nefarious equals method.
   */