* to equals(), and we will deduplicate those properly, albeit at some cost in allocations.
     */
    int expectedSize =
        elements instanceof Set ? array.length : estimatedSizeForUnknownDuplication(array.length);
    return fromArrayWithExpectedSize(array, expectedSize);
  }

  /**
   * Returns an immutable set containing each of {@code elements}, minus duplicates, in the order