*
     * @param <E> the element type of {@link TreeSet}
     * @return a new instance of {@link TreeSet}
     * @see TreeSet#TreeSet()
     */
    public static <E> TreeSet<E> newTreeSet() {
        return new TreeSet<>();
    }

    /**
     * Creates and returns a new instance of {@link TreeSet}.
     *
     * @param <E> the element type of {@link TreeSet}

    "rawtypes", // https://github.com/google/guava/issues/989
    "NonApiType", // acts as a direct substitute for a constructor call
  })
  public static <E extends Comparable> TreeSet<E> newTreeSet(Iterable<? extends E> elements) {
    TreeSet<E> set = newTreeSet();
    Iterables.addAll(set, elements);
    return set;
  }

  /**
   * Creates a <i>mutable</i>, empty {@code TreeSet} instance with the given comparator.
   *