*
     * @param model The model whose duplicate elements should be merged, must not be {@code null}.
     * @param request The model building request that holds further settings, must not be {@code null}.
     * @param problems The container used to collect problems that were encountered, must not be {@code null}.
     */

```

## Additional Responses

You probably have seen how to declare the `response_model` and `status_code` for a *path operation*.

That defines the metadata about the main response of a *path operation*.

You can also declare additional responses with their models, status codes, etc.

/**
 * Caches auxiliary data used during model building like already processed raw/effective models. The data in the cache
 * is meant for exclusive consumption by the model builder and is opaque to the cache implementation. The cache key is
 * formed by a combination of group id, artifact id, version and tag. The first three components generally refer to the

              <goal>xdoc</goal>
            </goals>
            <phase>pre-site</phase>
            <configuration>
              <version>1.0.0</version>
              <models>
                <model>src/main/mdo/extension.mdo</model>
              </models>
            </configuration>
          </execution>
        </executions>
      </plugin>
      <plugin>
        <groupId>org.codehaus.mojo</groupId>

    disabled = user_dict["disabled"],
    hashed_password = user_dict["hashed_password"],
)
```

!!! info
    For a more complete explanation of `**user_dict` check back in [the documentation for **Extra Models**](../extra-models.md#about-user_indict){.internal-link target=_blank}.

## Return the token

The response of the `token` endpoint must be a JSON object.

import pytest
from dirty_equals import IsDict
from fastapi.testclient import TestClient

from ...utils import needs_py39


@pytest.fixture(name="client")
def get_client():
    from docs_src.body_nested_models.tutorial009_py39 import app

    client = TestClient(app)
    return client


@needs_py39
def test_post_body(client: TestClient):
    data = {"2": 2.2, "3": 3.3}
    response = client.post("/index-weights/", json=data)

All the validation is handled by the well-established and robust **Pydantic**.

### Security and authentication

Security and authentication integrated. Without any compromise with databases or data models.

All the security schemes defined in OpenAPI, including:

* HTTP Basic.
* **OAuth2** (also with **JWT tokens**). Check the tutorial on [OAuth2 with JWT](tutorial/security/oauth2-jwt.md){.internal-link target=_blank}.

import org.apache.maven.api.model.Exclusion;
import org.apache.maven.api.model.Model;
import org.apache.maven.api.services.BuilderProblem.Severity;
import org.apache.maven.api.services.ModelBuilderRequest;
import org.apache.maven.api.services.ModelProblem.Version;
import org.apache.maven.api.services.ModelProblemCollector;
import org.apache.maven.api.services.model.*;

/**
 * Handles the import of dependency management from other models into the target model.

def fake_answer_to_everything_ml_model(x: float):
    return x * 42


ml_models = {}


@asynccontextmanager
async def lifespan(app: FastAPI):
    # Load the ML model
    ml_models["answer_to_everything"] = fake_answer_to_everything_ml_model
    yield
    # Clean up the ML models and release the resources
    ml_models.clear()


app = FastAPI(lifespan=lifespan)

import binascii
from base64 import b64decode
from typing import Optional

from fastapi.exceptions import HTTPException
from fastapi.openapi.models import HTTPBase as HTTPBaseModel
from fastapi.openapi.models import HTTPBearer as HTTPBearerModel
from fastapi.security.base import SecurityBase
from fastapi.security.utils import get_authorization_scheme_param
from pydantic import BaseModel
from starlette.requests import Request