code: @SafeVarargs
    public static <E> Set<E> of(E... elements) {
      Set<E> result = new HashSet<>();
      Collections.addAll(result, elements);
      return Collections.unmodifiableSet(result);
    }
docs: Returns an unmodifiable view of the set created from the given elements.
  
  @param elements Array of elements
  @param <E>      type of the elements
  @return an unmodifiable view of the set created from the given elements.