sub: SubModel


class ModelSubclass(Model):
    y: int
    z: int = 0
    w: int | None = None


class ModelDefaults(BaseModel):
    w: str | None = None
    x: str | None = None
    y: str = "y"
    z: str = "z"


@app.get("/", response_model=Model, response_model_exclude_unset=True)
def get_root() -> ModelSubclass:
    return ModelSubclass(sub={}, y=1, z=0)


@app.get(