callbacks=callback_router3.routes,
    dependencies=[Depends(dep3)],
    response_class=ResponseLevel3,
)
async def path3_override_router2_default(level3: str):
    return level3


@router2_default.get("/default3")
async def path3_default_router2_default(level3: str):
    return level3


@router4_override.get(
    "/override5",
    tags=["path5a", "path5b"],
    responses={

@app.get("/items/{item_id}")
def main(
    item_id: int = Path(default=..., gt=0),
    query: str = Query(default=..., max_length=10),
    session: str = Cookie(default=..., min_length=3),
    x_trace: str = Header(default=..., title="Tracing header"),
):
    return {"message": "Hello World"}
```

...all these parameters are required because the default value is `...` (Ellipsis).