That means that, clients using your API don't have to check if the value exists or not, they can **assume the field will always be there**, but just that in some cases it will have the default value of `None`.

The way to describe this in OpenAPI, is to mark that field as **required**, because it will always be there.

Because of that, the JSON Schema for a model can be different depending on if it's used for **input or output**:

Aqui estão várias formas de se fazer isso.

## `schema_extra` do Pydantic

Você pode declarar um `example` para um modelo Pydantic usando `Config` e `schema_extra`, conforme descrito em <a href="https://docs.pydantic.dev/latest/concepts/json_schema/#schema-customization" class="external-link" target="_blank">Documentação do Pydantic: Schema customization</a>:

```Python hl_lines="15-23"

# Using TensorFlow Securely

This document discusses the TensorFlow security model. It describes the security
risks to consider when using models, checkpoints or input data for training or
serving. We also provide guidelines on what constitutes a vulnerability in
TensorFlow and how to report them.

This document applies to other repositories in the TensorFlow organization,
covering security practices for the entirety of the TensorFlow ecosystem.

  optional string subresource = 1;

  // responseKind describes the group, version, and kind of the serialization schema for the object type this endpoint typically returns.
  // Some subresources do not return normal resources, these will have null return types.
  optional k8s.io.apimachinery.pkg.apis.meta.v1.GroupVersionKind responseKind = 2;

  // acceptedTypes describes the kinds that this endpoint accepts.

You can also declare the `Response` parameter in dependencies, and set headers (and cookies) in them.

## Return a `Response` directly

You can also add headers when you return a `Response` directly.

Create a response as described in [Return a Response Directly](response-directly.md){.internal-link target=_blank} and pass the headers as an additional parameter:

```Python hl_lines="10-12"
{!../../../docs_src/response_headers/tutorial001.py!}
```

## Example

For a simple example, let's consider a file structure similar to the one described in [Bigger Applications](../tutorial/bigger-applications.md){.internal-link target=_blank} and [Testing](../tutorial/testing.md){.internal-link target=_blank}:

```
.
├── app
│   ├── __init__.py
│   ├── main.py

import okhttp3.internal.immutableListOf
import okhttp3.internal.toImmutableList

/**
 * A record of a TLS handshake. For HTTPS clients, the client is *local* and the remote server is
 * its *peer*.
 *
 * This value object describes a completed handshake. Use [ConnectionSpec] to set policy for new
 * handshakes.
 */
class Handshake internal constructor(
  /**

# Istio Agent

This document describes the internal architecture of Istio agent.

## High Level overview

![High Level overview](docs/overview.svg)

At a high level, the Istio agent acts as an intermediate proxy between Istiod and Envoy. This is done
at two levels. For distributing workload certificates, Envoy will send [SDS](https://www.envoyproxy.io/docs/envoy/latest/configuration/security/secret)

  private val inflater =
    Inflater(
      // nowrap (omits zlib header):
      true,
    )

  private val inflaterSource = InflaterSource(deflatedBytes, inflater)

  /** Inflates [buffer] in place as described in RFC 7692 section 7.2.2. */
  @Throws(IOException::class)
  fun inflate(buffer: Buffer) {
    require(deflatedBytes.size == 0L)

    if (noContextTakeover) {
      inflater.reset()
    }

    Deflater(
      Deflater.DEFAULT_COMPRESSION,
      // nowrap (omits zlib header):
      true,
    )

  private val deflaterSink = DeflaterSink(deflatedBytes, deflater)

  /** Deflates [buffer] in place as described in RFC 7692 section 7.2.1. */
  @Throws(IOException::class)
  fun deflate(buffer: Buffer) {
    require(deflatedBytes.size == 0L)

    if (noContextTakeover) {
      deflater.reset()
    }