original.put("one", 1);
    original.put("two", 2);
    original.put("three", 3);

    ImmutableSortedMap<String, Integer> copy = ImmutableSortedMap.copyOfSorted(original);
    assertMapEquals(copy, "one", 1, "three", 3, "two", 2);
    assertSame(copy, ImmutableSortedMap.copyOfSorted(copy));
    assertSame(Ordering.natural(), copy.comparator());
  }

  public void testCopyOfSortedExplicit() {

   * When multiple elements are equivalent according to {@code compareTo()}, only the first one
   * specified is included. To create a copy of a {@code SortedSet} that preserves the comparator,
   * call {@link #copyOfSorted} instead. This method iterates over {@code elements} at most once.
   *
   * <p>Note that if {@code s} is a {@code Set<String>}, then {@code ImmutableSortedSet.copyOf(s)}

    checkNotNull(mergeFunction);
    return Collectors.collectingAndThen(
        Collectors.toMap(
            keyFunction, valueFunction, mergeFunction, () -> new TreeMap<K, V>(comparator)),
        ImmutableSortedMap::copyOfSorted);
  }

  // unsafe, comparator() returns a comparator on the specified type
  @SuppressWarnings("unchecked")
  public static <K, V> ImmutableSortedMap<K, V> of() {

    SortedSet<String> set = ImmutableSortedSet.copyOfSorted(input);
    assertThat(set).containsExactly("a", "in", "jumped", "over", "quick", "the").inOrder();
  }

  public void testCopyOfSorted_natural_comparator() {
    SortedSet<String> input = Sets.newTreeSet(asList("in", "the", "quick", "jumped", "over", "a"));
    SortedSet<String> set = ImmutableSortedSet.copyOfSorted(input);
    assertSame(Ordering.natural(), set.comparator());

    return copyOfInternal(comparator, elements);
  }

  // We use NATURAL_ORDER only if the input was already using natural ordering.
  @SuppressWarnings("unchecked")
  public static <E> ImmutableSortedSet<E> copyOfSorted(SortedSet<E> sortedSet) {
    Comparator<? super E> comparator = sortedSet.comparator();
    if (comparator == null) {
      comparator = (Comparator<? super E>) NATURAL_ORDER;
    }

 * usually include:
 *
 * <ul>
 *   <li>Static methods named {@code of}, accepting an explicit list of elements or entries.
 *   <li>Static methods named {@code copyOf} (or {@code copyOfSorted}), accepting an existing
 *       collection whose contents should be copied.
 *   <li>A static nested {@code Builder} class which can be used to populate a new immutable
 *       instance.
 * </ul>
 *

 * usually include:
 *
 * <ul>
 *   <li>Static methods named {@code of}, accepting an explicit list of elements or entries.
 *   <li>Static methods named {@code copyOf} (or {@code copyOfSorted}), accepting an existing
 *       collection whose contents should be copied.
 *   <li>A static nested {@code Builder} class which can be used to populate a new immutable
 *       instance.
 * </ul>
 *