http.response.status_code as long instead of keyword or integer

Hello ,
I did not found any discussion on this topic so , I ask the question
In ECS the `http.response.status_code` is mapped as long , why ?

Using an integer brings the advantage of taking up less space, but we are not supposed to do digital operations (sum/avg...) on an HTTP status because all codes are between 100 and 599.

Using a keyword will allow to run an aggregation without specifying a null_value.
The keyword type will also allow to make range query if necessary (it will be in alphanumeric order):
[ECS source code](https://github.com/elastic/ecs/blob/master/schemas/http.yml#L36)
```
- name: response.status_code
format: string
level: extended
type: long
description: >
HTTP response status code.
example: 404
```