state.router_shutdown = True

    sub_router = APIRouter()

    @sub_router.on_event("startup")
    def sub_router_startup() -> None:
        state.sub_router_startup = True

    @sub_router.on_event("shutdown")
    def sub_router_shutdown() -> None:
        state.sub_router_shutdown = True

    router.include_router(sub_router)
    app.include_router(router)

        return item1, item2  # pragma: nocover

    @sub_router.post(
        "/subrouter",
        response_model=list[Item],
        responses={404: {"model": list[Message]}},
    )
    def post_subrouter(item1: Item, item2: Item):
        return item1, item2  # pragma: nocover

    router.include_router(sub_router)
    app.include_router(router, generate_unique_id_function=custom_generate_unique_id3)

events_callback_router = APIRouter()


@events_callback_router.get("{$callback_url}/events/{$request.body.title}")
def event_callback(event: Event):
    pass  # pragma: nocover


subrouter = APIRouter()


@subrouter.post("/invoices/", callbacks=invoices_callback_router.routes)
def create_invoice(invoice: Invoice, callback_url: Optional[HttpUrl] = None):
    """
    Create an invoice.