* Note that when {@code containsKey(key)} is false, this returns an empty collection, not {@code
   * null}.
   *
   * <p>Changes to the returned collection will update the underlying multimap, and vice versa.
   */
  Collection<V> get(@ParametricNullness K key);

  /**
   * Returns a view collection of all <i>distinct</i> keys contained in this multimap. Note that the

      new ImmutableClassToInstanceMap<>(ImmutableMap.<Class<?>, Object>of());

  /**
   * Returns an empty {@code ImmutableClassToInstanceMap}.
   *
   * <p><b>Performance note:</b> the instance returned is a singleton.
   *
   * @since 19.0
   */
  @SuppressWarnings("unchecked")
  public static <B> ImmutableClassToInstanceMap<B> of() {
    return (ImmutableClassToInstanceMap<B>) EMPTY;
  }

당연하게 `Path`, `Query` 및 요청 본문 매개변수 선언을 자유롭게 혼합해서 사용할 수 있고, **FastAPI**는 어떤 동작을 할지 압니다.

또한, 기본 값을 `None`으로 설정해 본문 매개변수를 선택사항으로 선언할 수 있습니다.

{* ../../docs_src/body_multiple_params/tutorial001.py hl[19:21] *}

/// note | 참고

이 경우에는 본문으로 부터 가져온 `	item`은 기본값이 `None`이기 때문에, 선택사항이라는 점을 유의해야 합니다.

///

## 다중 본문 매개변수

이전 예제에서 보듯이, *경로 작동*은 아래와 같이 `Item` 속성을 가진 JSON 본문을 예상합니다:

```JSON
{
    "name": "Foo",

Por ejemplo, para declarar un valor de metadato `title` para el parámetro de path `item_id` puedes escribir:

{* ../../docs_src/path_params_numeric_validations/tutorial001_an_py310.py hl[10] *}

/// note | Nota

Un parámetro de path siempre es requerido ya que tiene que formar parte del path. Incluso si lo declaras con `None` o le asignas un valor por defecto, no afectará en nada, siempre será requerido.

///

     * <ul>
     *     <li>System properties (lowest precedence)</li>
     *     <li>Project properties (optional)</li>
     *     <li>User properties (highest precedence)</li>
     * </ul>
     * Note: Project properties contains properties injected from profiles, if applicable. Their precedence is
     * {@code profile > project}, hence active profile property may override project property.
     * <p>

 *
 * <p>However, when {@link CollectionSize.Require} is used to annotate a test it behaves normally
 * (i.e. it requires the collection instance under test to be a certain size for the test to run).
 * Note that this means a test should not require more than one CollectionSize, since a particular
 * collection instance can only be one size at once.
 *
 * @author George van den Driessche
 */

 * iterator} method only once, and should be tested using this class. Exceptions to this rule should
 * be clearly documented.
 *
 * <p>Note that although your APIs should be liberal in what they accept, your methods which
 * <i>return</i> iterables should make every attempt to return ones of the robust variety.
 *
 * <p>This testing utility is not thread-safe.
 *

 *
 * <p>However, when {@link CollectionSize.Require} is used to annotate a test it behaves normally
 * (i.e. it requires the collection instance under test to be a certain size for the test to run).
 * Note that this means a test should not require more than one CollectionSize, since a particular
 * collection instance can only be one size at once.
 *
 * @author George van den Driessche
 */

Это позволит вам **переиспользовать модель** в **разных местах**, а также объявить проверки и метаданные сразу для всех параметров. 😎

/// note | Заметка

Этот функционал доступен с версии `0.115.0`. 🤓

///

/// tip | Совет

Такой же подход применяется для `Query`, `Cookie`, и `Header`. 😎

///

## Pydantic-модель для cookies

O primeiro valor é o valor padrão, você pode passar todas as validações adicionais ou parâmetros de anotação:

{* ../../docs_src/header_params/tutorial001_py310.py hl[7] *}

/// note | Detalhes Técnicos

`Header` é uma classe "irmã" de `Path`, `Query` e `Cookie`. Ela também herda da mesma classe em comum `Param`.