If you go to `/docs`, you will see that it has the **schemas** for the data to be sent in requests and received in responses:

<img src="/img/tutorial/generate-clients/image01.png">

You can see those schemas because they were declared with the models in the app.

That information is available in the app's **OpenAPI schema**, and then shown in the API docs.

    public void testMethodOverrides() throws NoSuchMethodException {
        // Given
        Class<?> clazz = SmbComTreeDisconnect.class;

        // When & Then - verify methods are declared in this class (overridden)
        Method writeParameterWords = clazz.getDeclaredMethod("writeParameterWordsWireFormat", byte[].class, int.class);
        assertNotNull(writeParameterWords);

            assertNotNull(e.getCause());
            assertTrue(e.getCause() instanceof IllegalArgumentException);
        }
    }

    /**
     * Test exception in method that declares throws
     */
    public void test_exceptionInMethod() {
        try {
            methodThatThrowsException();
            fail("Should have thrown CrawlerSystemException");

    }

    /**
     * Test all fields are public and accessible
     */
    @Test
    @DisplayName("Test all fields are public")
    public void testAllFieldsArePublic() {
        // Get all declared fields
        Field[] fields = ServerData.class.getDeclaredFields();

        // Verify we have the expected number of fields
        assertEquals(19, fields.length);

        // Verify all fields are public

      <artifactId>guava</artifactId>
      <version>${project.version}</version>
    </dependency>
    <!-- We redeclare the j2objc-annotations dependency from `guava`: Our Gradle
         Module Metadata hides the dependency declared in `guava` from runtime
         configurations downstream, and GWT uses the runtime configuration for
         its builds. Thus, GWT doesn't get j2objc-annotations transitively, in

     *       module path, but is also compatible with placement on the class path. Compatibility can
     *       be achieved, for example, by repeating in the {@code META-INF/services/} directory the services
     *       that are declared in the {@code module-info.class} file. In that case, the path type can be chosen
     *       by the plugin.</li>
     *   <li>If a {@link #patchModule(String)} is also set and the main JAR file is placed on the module path,

But if you return a `Response` directly (or any subclass, like `JSONResponse`), the data won't be automatically converted (even if you declare a `response_model`), and the documentation won't be automatically generated (for example, including the specific "media type", in the HTTP header `Content-Type` as part of the generated OpenAPI).

* Des techniques plus avancées (mais tout aussi faciles) pour déclarer les **modèles <abbr title="JavaScript Object Notation">JSON</abbr> profondément imbriqués** (grâce à Pydantic).

Se você tem certo conhecimento técnico (corrotinas, threads, blocking etc) e está curioso sobre como o FastAPI controla o `async def` vs normal `def`, vá em frente.

///

### Funções de operação de rota

Quando você declara uma *função de operação de rota* com `def` normal ao invés de `async def`, ela é rodada em uma threadpool externa que é então aguardada, ao invés de ser chamada diretamente (já que ela bloquearia o servidor).

It will include all the routes from that router as part of it.

/// note | Technical Details

It will actually internally create a *path operation* for each *path operation* that was declared in the `APIRouter`.

So, behind the scenes, it will actually work as if everything was the same single app.

///

/// check

You don't have to worry about performance when including routers.