unreleased.add(getLatestVersionByKey(groupByMinor, greatestMinor - 2));
                }
            }
        }

        return unmodifiableList(unreleased.stream().sorted().distinct().collect(Collectors.toList()));
    }

    private Version getLatestInMinor(int major, int minor) {
        return groupByMajor.get(major).stream().filter(v -> v.getMinor() == minor).max(Version::compareTo).orElse(null);

    }

    @Override
    public Multiset<K> create(Object... elements) {
      /*
       * This is nasty and complicated, but it's the only way to make sure keys get mapped to enough
       * distinct values.
       */
      Entry<?, ?>[] entries = new Entry<?, ?>[elements.length];
      Map<K, Iterator<V>> valueIterators = new HashMap<>();
      for (int i = 0; i < elements.length; i++) {

 *
 * <p>A non-null {@code Optional<T>} reference can be used as a replacement for a nullable {@code T}
 * reference. It allows you to represent "a {@code T} that must be present" and a "a {@code T} that
 * might be absent" as two distinct types in your program, which can aid clarity.
 *
 * <p>Some uses of this class include
 *
 * <ul>
 *   <li>As a method return type, as an alternative to returning {@code null} to indicate that no

   * arrays. Like {@code Joiner}, it is thread-safe and immutable.
   *
   * <p>In addition to operating on {@code Map} instances, {@code MapJoiner} can operate on {@code
   * Multimap} entries in two distinct modes:
   *
   * <ul>
   *   <li>To output a separate entry for each key-value pair, pass {@code multimap.entries()} to a
   *       {@code MapJoiner} method that accepts entries as input, and receive output of the form

   *
   * <p><b>Warning: do not depend</b> on the behavior of this method.
   *
   * <p>Historically, {@code Equivalence} instances in this library have implemented this method to
   * recognize certain cases where distinct {@code Equivalence} instances would in fact behave
   * identically. However, as code migrates to {@code java.util.function}, that behavior will
   * disappear. It is best not to depend on it.
   */
  @Override

   * arrays. Like {@code Joiner}, it is thread-safe and immutable.
   *
   * <p>In addition to operating on {@code Map} instances, {@code MapJoiner} can operate on {@code
   * Multimap} entries in two distinct modes:
   *
   * <ul>
   *   <li>To output a separate entry for each key-value pair, pass {@code multimap.entries()} to a
   *       {@code MapJoiner} method that accepts entries as input, and receive output of the form

   * Arrays#asList(Object[])}. The list supports {@link List#set(int, Object)}, but any attempt to
   * set a value to {@code null} will result in a {@link NullPointerException}.
   *
   * <p>There are at most two distinct objects in this list, {@code (Boolean) true} and {@code
   * (Boolean) false}. Java guarantees that those are always represented by the same objects.
   *
   * <p>The returned list is serializable.
   *

                    Arrays.spliterator(new String[] {"abc", "", "de", "f", "g", ""}),
                    (String str) -> charactersOf(str).spliterator(),
                    Spliterator.SIZED | Spliterator.DISTINCT | Spliterator.NONNULL,
                    7))
        .expect('a', 'b', 'c', 'd', 'e', 'f', 'g');
  }

  public void testFlatMap_nullStream() {
    SpliteratorTester.of(
            () ->

   * inequality.
   */
  protected final <T> void setDefault(Class<T> type, T value) {
    tester.setDefault(type, value);
  }

  /**
   * Sets two distinct values for {@code type}. These values can be used for both null pointer
   * testing and equals testing.
   *
   * @since 17.0
   */
  protected final <T> void setDistinctValues(Class<T> type, T value1, T value2) {

    }

    @Override
    public Multiset<K> create(Object... elements) {
      /*
       * This is nasty and complicated, but it's the only way to make sure keys get mapped to enough
       * distinct values.
       */
      Entry<?, ?>[] entries = new Entry<?, ?>[elements.length];
      Map<K, Iterator<V>> valueIterators = new HashMap<>();
      for (int i = 0; i < elements.length; i++) {