SAM Conversions
---------------

When you use Java APIs from Kotlin you can operate on Java interfaces as if they were Kotlin
lambdas. The [feature][java_sams] is available for interfaces that define a Single Abstract Method
(SAM).

But when you use Kotlin APIs from Kotlin there’s no automatic conversion. Code that used SAM lambdas
with OkHttp 3.x: must use `object :` with OkHttp 4.x:

        transformValues(
            underlying,
            new Function<@Nullable String, Boolean>() {
              @Override
              public Boolean apply(@Nullable String from) {
                return from == null;
              }
            });
    Map<String, Boolean> expected = ImmutableMap.of("a", true, "b", false);
    assertMapsEqual(expected, map);
    assertEquals(expected.get("a"), map.get("a"));

                // Don't want to have two workers pulling from the queue.
                return;
              } else {
                // Increment the run counter to avoid the ABA problem of a submitter marking the
                // thread as QUEUED after it already ran and exhausted the queue before returning
                // from execute().
                workerRunCount++;

  <span style="background-color:#009485"><font color="#D3D7CF"> FastAPI </font></span>  Starting development server 🚀

             Searching for package file structure from directories with
             <font color="#3465A4">__init__.py</font> files
             Importing from <font color="#75507B">/home/user/code/</font><font color="#AD7FA8">awesomeapp</font>

from collections.abc import AsyncGenerator
from contextlib import asynccontextmanager

import pytest
from fastapi import APIRouter, FastAPI, Request
from fastapi.testclient import TestClient
from pydantic import BaseModel


class State(BaseModel):
    app_startup: bool = False
    app_shutdown: bool = False
    router_startup: bool = False
    router_shutdown: bool = False
    sub_router_startup: bool = False

from typing import Annotated

from fastapi import FastAPI, Header
from pydantic import BaseModel

app = FastAPI()


class CommonHeaders(BaseModel):
    model_config = {"extra": "forbid"}

    host: str
    save_data: bool
    if_modified_since: str | None = None
    traceparent: str | None = None
    x_tag: list[str] = []


@app.get("/items/")
async def read_items(headers: Annotated[CommonHeaders, Header()]):

from typing import Annotated

from fastapi import FastAPI, File, UploadFile

app = FastAPI()


@app.post("/files/")
async def create_file(file: Annotated[bytes, File()]):
    return {"file_size": len(file)}


@app.post("/uploadfile/")
async def create_upload_file(file: UploadFile):

from fastapi import FastAPI
from fastapi.testclient import TestClient

app = FastAPI()

items = {}


@app.on_event("startup")
async def startup_event():
    items["foo"] = {"name": "Fighters"}
    items["bar"] = {"name": "Tenders"}


@app.get("/items/{item_id}")
async def read_items(item_id: str):
    return items[item_id]


def test_read_items():
    with TestClient(app) as client:

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None
    tags: list[str] = []


@app.post("/items/")
async def create_item(item: Item) -> Item:
    return item


@app.get("/items/")
async def read_items() -> list[Item]:
    return [

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None

    model_config = {
        "json_schema_extra": {
            "examples": [
                {
                    "name": "Foo",
                    "description": "A very nice Item",
                    "price": 35.4,