}
  }

  /**
   * Returns a new {@link TypeVariable} that belongs to {@code declaration} with {@code name} and
   * {@code bounds}.
   */
  static <D extends GenericDeclaration> TypeVariable<D> newArtificialTypeVariable(
      D declaration, String name, Type... bounds) {
    return newTypeVariableImpl(
        declaration, name, (bounds.length == 0) ? new Type[] {Object.class} : bounds);
  }

/**
 * Tester of subtyping relationships between two types.
 *
 * <p>Tests should inherit from this class, and declare subtyping relationship with public methods
 * annotated by {@link TestSubtype}.
 *
 * <p>These declaration methods rely on Java static type checking to make sure what we want to
 * assert as subtypes are really subtypes according to javac. For example:
 *
 * {@snippet :
 * class MySubtypeTests extends SubtypeTester {

of the last non-empty expression list.
</p>


<h3 id="Type_declarations">Type declarations</h3>

<p>
A type declaration binds an identifier, the <i>type name</i>, to a <a href="#Types">type</a>.
Type declarations come in two forms: alias declarations and type definitions.
</p>

<pre class="ebnf">
TypeDecl = "type" ( TypeSpec | "(" { TypeSpec ";" } ")" ) .

**FastAPI** vous offre ceci:

### Basé sur des standards ouverts

    }
  }

  /**
   * Returns a new {@link TypeVariable} that belongs to {@code declaration} with {@code name} and
   * {@code bounds}.
   */
  static <D extends GenericDeclaration> TypeVariable<D> newArtificialTypeVariable(
      D declaration, String name, Type... bounds) {
    return newTypeVariableImpl(
        declaration, name, (bounds.length == 0) ? new Type[] {Object.class} : bounds);
  }

Cela vous donne beaucoup de flexibilité. Vous pouvez retourner n'importe quel type de données, surcharger n'importe quelle déclaration ou validation de données.

## Utiliser le `jsonable_encoder` dans une `Response`

To create the callback *path operation* use the same `APIRouter` you created above.

It should look just like a normal FastAPI *path operation*:

* It should probably have a declaration of the body it should receive, e.g. `body: InvoiceEvent`.
* And it could also have a declaration of the response it should return, e.g. `response_model=InvoiceEventReceived`.

{* ../../docs_src/openapi_callbacks/tutorial001.py hl[16:18,21:22,28:32] *}

    /**
     * Returns an immutable list of project remote repositories (directly specified or inherited).
     * The repositories are ordered by declaration order, with inherited repositories appearing
     * after directly specified ones.
     *
     * @param project the project
     * @return ordered list of remote repositories
     */
    @Nonnull

///

## Duplicate headers { #duplicate-headers }

It is possible to receive duplicate headers. That means, the same header with multiple values.

You can define those cases using a list in the type declaration.

You will receive all the values from the duplicate header as a Python `list`.

For example, to declare a header of `X-Token` that can appear more than once, you can write:

It won't do any data conversion with Pydantic models, it won't convert the contents to any type, etc.

This gives you a lot of flexibility. You can return any data type, override any data declaration or validation, etc.

## Using the `jsonable_encoder` in a `Response` { #using-the-jsonable-encoder-in-a-response }