throw new IllegalStateException("Optional.get() cannot be called on an absent value");
  }

  @Override
  public T or(T defaultValue) {
    return checkNotNull(defaultValue, "use Optional.orNull() instead of Optional.or(null)");
  }

  @SuppressWarnings("unchecked") // safe covariant cast
  @Override
  public Optional<T> or(Optional<? extends T> secondChoice) {
    return (Optional<T>) checkNotNull(secondChoice);
  }

You can define arbitrarily deeply nested models:

{* ../../docs_src/body_nested_models/tutorial007_py310.py hl[7,12,18,21,25] *}

/// info

Notice how `Offer` has a list of `Item`s, which in turn have an optional list of `Image`s

///

## Bodies of pure lists { #bodies-of-pure-lists }

  public void testEmptiesFirst() {
    Optional<String> empty = Optional.empty();
    Optional<String> abc = Optional.of("abc");
    Optional<String> z = Optional.of("z");

    Comparator<Optional<String>> comparator = emptiesFirst(comparing(String::length));
    testComparator(comparator, empty, z, abc);

    // Just demonstrate that no explicit type parameter is required
    Comparator<Optional<String>> unused = emptiesFirst(naturalOrder());

     *
     * @return An Optional containing the lowest matching version, or empty Optional if no versions
     *         matched the requested range
     */
    @Nonnull
    default Optional<Version> getLowestVersion() {
        return getVersions().isEmpty()
                ? Optional.empty()
                : Optional.of(getVersions().get(0));
    }

    /**

            @Nonnull
            @Override
            public Optional<Source> getInstallationSettingsSource() {
                return Optional.ofNullable(installationSettingsSource);
            }

            @Nonnull
            @Override
            public Optional<Source> getProjectSettingsSource() {
                return Optional.ofNullable(projectSettingsSource);
            }

            @Nonnull

            this.scope = scope;
            return this;
        }

        public DependencyCoordinatesFactoryRequestBuilder optional(boolean optional) {
            this.optional = optional;
            return this;
        }

        public DependencyCoordinatesFactoryRequestBuilder exclusions(Collection<Exclusion> exclusions) {
            if (exclusions != null) {

  @Override
  public T get() {
    return reference;
  }

  @Override
  public T or(T defaultValue) {
    checkNotNull(defaultValue, "use Optional.orNull() instead of Optional.or(null)");
    return reference;
  }

  @Override
  public Optional<T> or(Optional<? extends T> secondChoice) {
    checkNotNull(secondChoice);
    return this;
  }

  @Override
  public T or(Supplier<? extends T> supplier) {

Das ist keine Limitation von **FastAPI**, sondern Teil des HTTP-Protokolls.

///

## Optionaler Datei-Upload

Sie können eine Datei optional machen, indem Sie Standard-Typannotationen verwenden und den Defaultwert auf `None` setzen:

{* ../../docs_src/request_files/tutorial001_02_an_py310.py hl[9,17] *}

 * to add or remove multiple occurrences of an element at once, or to set the count of an element to
 * a specific value. These modification operations are optional, but implementations which support
 * the standard collection operations {@link #add(Object)} or {@link #remove(Object)} are encouraged
 * to implement the related methods as well. Finally, two collection views are provided: {@link

        // v1 == 0.
        .optional(defaultValue = 0),
      Adapters.INTEGER_AS_BIG_INTEGER,
      algorithmIdentifier,
      name,
      validity,
      name,
      subjectPublicKeyInfo,
      Adapters.BIT_STRING.withTag(tag = 1L).optional(),
      Adapters.BIT_STRING.withTag(tag = 2L).optional(),
      extension.asSequenceOf().withExplicitBox(tag = 3).optional(defaultValue = listOf()),
      decompose = {