final LdapManager ldapManager = ComponentUtil.getLdapManager();
                permissions = distinct(ArrayUtils.addAll(ldapManager.getRoles(this, baseDn, accountFilter, groupFilter, roles -> {
                    permissions = distinct(roles);
                    ComponentUtil.getActivityHelper().permissionChanged(OptionalThing.of(new FessUserBean(this)));

                    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(
            () ->

   * a map serialized by {@link #writeMap(Map, ObjectOutputStream)}, the number of distinct elements
   * in a multiset serialized by {@link #writeMultiset(Multiset, ObjectOutputStream)}, or the number
   * of distinct keys in a multimap serialized by {@link #writeMultimap(Multimap,
   * ObjectOutputStream)}.
   */

    return new HashMultiset<>();
  }

  /**
   * Creates a new, empty {@code HashMultiset} with the specified expected number of distinct
   * elements.
   *
   * @param distinctElements the expected number of distinct elements
   * @throws IllegalArgumentException if {@code distinctElements} is negative
   */
  public static <E extends @Nullable Object> HashMultiset<E> create(int distinctElements) {

   * a map serialized by {@link #writeMap(Map, ObjectOutputStream)}, the number of distinct elements
   * in a multiset serialized by {@link #writeMultiset(Multiset, ObjectOutputStream)}, or the number
   * of distinct keys in a multimap serialized by {@link #writeMultimap(Multimap,
   * ObjectOutputStream)}.
   */

      ArrayList<V> arrayList = (ArrayList<V>) collection;
      arrayList.trimToSize();
    }
  }

  /**
   * @serialData expectedValuesPerKey, number of distinct keys, and then for each distinct key: the
   *     key, number of values for that key, and the key's values
   */
  @GwtIncompatible
  @J2ktIncompatible
    private void writeObject(ObjectOutputStream stream) throws IOException {

    // "extends Object" works around https://github.com/typetools/checker-framework/issues/3013
    SerializedForm(Multiset<? extends Object> multiset) {
      int distinct = multiset.entrySet().size();
      elements = new Object[distinct];
      counts = new int[distinct];
      int i = 0;
      for (Entry<? extends Object> entry : multiset.entrySet()) {
        elements[i] = entry.getElement();
        counts[i] = entry.getCount();

        this.defaultValue = defaultValue;
    }

    /**
     * Gets all distinct file types currently configured in the mappings.
     *
     * @return an array of all unique file type values
     */
    public String[] getTypes() {
        return mimetypeMap.values().stream().distinct().toArray(n -> new String[n]);
    }

    @Override
    public String getQuery() {
        return q;
    }

    @Override
    public String[] getExtraQueries() {
        return stream(ex_q).get(stream -> stream.filter(StringUtil::isNotBlank).distinct().toArray(n -> new String[n]));
    }

    @Override
    public Map<String, String[]> getFields() {
        return fields;
    }

    @Override
    public Map<String, String[]> getConditions() {

  @Nullable Entry<E> firstEntry();

  @Nullable Entry<E> lastEntry();

  @Nullable Entry<E> pollFirstEntry();

  @Nullable Entry<E> pollLastEntry();

  /**
   * Returns a {@link SortedSet} view of the distinct elements in this multiset. (Outside GWT, this
   * returns a {@code NavigableSet}.)
   */
  @Override
  SortedSet<E> elementSet();

  SortedMultiset<E> descendingMultiset();