from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel as BaseModelV2
from pydantic.v1 import BaseModel


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    size: float


class ItemV2(BaseModelV2):
    name: str
    description: Union[str, None] = None
    size: float


app = FastAPI()


@app.post("/items/", response_model=ItemV2)

import common.Os
import jetbrains.buildServer.configs.kotlin.BuildType
import model.Stage

open class BaseGradleBuildType(
    open val stage: Stage? = null,
    open val failStage: Boolean = true,
    init: BaseGradleBuildType.() -> Unit = {},
) : BuildType() {
    init {
        this.init()
    }
}

open class OsAwareBaseGradleBuildType(
    val os: Os,
    override val stage: Stage? = null,

from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None


class User(BaseModel):
    username: str
    full_name: Union[str, None] = None


@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item, user: User):

//      from the plugin archive.
// TODO this will be the class that people get in IDEs to modify

/**
 * MavenExecutionPlan
 */
public class MavenExecutionPlan implements Iterable<ExecutionPlanItem> {

    /*
      At the moment, this class is totally immutable, and this is in line with thoughts about the

* <a href="https://github.com/encode/uvicorn/blob/master/uvicorn/middleware/proxy_headers.py" class="external-link" target="_blank">Uvicorn's `ProxyHeadersMiddleware`</a>
* <a href="https://github.com/florimondmanca/msgpack-asgi" class="external-link" target="_blank">MessagePack</a>

* <a href="https://github.com/florimondmanca/msgpack-asgi" class="external-link" target="_blank">MessagePack</a>

from typing import Union

from fastapi import Body, FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None


class User(BaseModel):
    username: str
    full_name: Union[str, None] = None


@app.put("/items/{item_id}")

import org.codehaus.plexus.configuration.PlexusConfiguration;

import static java.util.Objects.requireNonNull;

/**
 * Common implementations for plugin parameters configuration validation.
 *
 */
abstract class AbstractMavenPluginParametersValidator implements MavenPluginConfigurationValidator {

    protected final PluginValidationManager pluginValidationManager;

/**
 * Assists in firing execution events. <strong>Warning:</strong> This is an internal utility class that is only public
 * for technical reasons, it is not part of the public API. In particular, this class can be changed or deleted without
 * prior notice.
 *
 */
@Named
@Singleton
public class DefaultExecutionEventCatapult implements ExecutionEventCatapult {

    @Override

Actually, `Query`, `Path` and others you'll see next create objects of subclasses of a common `Param` class, which is itself a subclass of Pydantic's `FieldInfo` class.

And Pydantic's `Field` returns an instance of `FieldInfo` as well.

`Body` also returns objects of a subclass of `FieldInfo` directly. And there are others you will see later that are subclasses of the `Body` class.