///

A única coisa nova é o argumento `callbacks=invoices_callback_router.routes` no decorador da *operação de rota*. Veremos o que é isso a seguir.

## Documentando o callback

O código real do callback dependerá muito do seu próprio aplicativo de API.

E provavelmente variará muito de um aplicativo para o outro.

Poderia ser apenas uma ou duas linhas de código, como:

```Python

    attributes:
      label: Context (optional)
      description: |
        How has this issue affected you? What are you trying to accomplish?
        Providing context helps us come up with a solution that is most useful in the real world
    validations:
      required: false
  - type: textarea
    id: steps-to-reproduce
    attributes:
      label: Self-contained Reproducer Project
      description: |

If you integrate your API with an OAuth2 provider, you will be able to authenticate and come back to the API docs with the acquired credentials. And interact with it using the real OAuth2 authentication.

Swagger UI will handle it behind the scenes for you, but it needs this "redirect" helper.

///

### Create a *path operation* to test it

    @SuppressWarnings("nullness") // safe because we pass sort() a range that contains real Ts
    T[] castBuffer = (T[]) buffer;
    sort(castBuffer, 0, bufferSize, comparator);
    if (bufferSize > k) {
      Arrays.fill(buffer, k, buffer.length, null);
      bufferSize = k;
      threshold = buffer[k - 1];
    }
    // Up to bufferSize, all elements of buffer are real Ts (not null unless T includes null)

- **[DPE University Free Courses](https://dpeuniversity.gradle.com/app/catalog)**: A collection of hands-on courses for learning Gradle, complete with project-based tasks to improve real-world skills.
- **[Gradle Community Resources](https://community.gradle.org/resources/)**: Discover a range of resources, tutorials, and guides to support your Gradle journey, from foundational concepts to advanced practices.

Se você integrar sua API com um provedor OAuth2, você poderá autenticar e voltar para a documentação da API com as credenciais adquiridas. E interagir com ela usando a autenticação OAuth2 real.

Swagger UI lidará com isso nos bastidores para você, mas ele precisa desse auxiliar de "redirecionamento".

///

### Criar uma *operação de rota* para testar

    attributes:
      label: Context (optional)
      description: |
        How has this issue affected you? What are you trying to accomplish?
        Providing context helps us come up with a solution that is most useful in the real world
    validations:
      required: false
  - type: textarea
    id: steps-to-reproduce
    attributes:
      label: Self-contained Reproducer Project
      description: |

     * whether the DependencyCoordinates is used in dependency management, in which case it means the scope is not
     * explicitly managed by this managed dependency, or as a real dependency, in which case, the scope
     * will default to {@link #COMPILE}.
     */
    UNDEFINED("", false),

    /**
     * Compile only.
     */
    COMPILE_ONLY("compile-only", false),

    /**

///

/// info

In this example we use invented custom headers `X-Key` and `X-Token`.

But in real cases, when implementing security, you would get more benefits from using the integrated [Security utilities (the next chapter)](../security/index.md){.internal-link target=_blank}.

///

## Dependencies errors and return values

input size | lib | MB/s | Allocated
--- | --- | --- | ---
regular | standard | 97 | 3.6MB
regular | jstream | 175 | 2.1MB
large | standard | 92 | 305MB
large | jstream | 404 | 69MB

In a real world scenario, including initialization and reader overhead from varying blob sizes, performance can be expected as below: