Application Settings `enabled_git_access_protocol` cannot be set to `null`

[timofurrer]

The enabled_git_access_protocol field in the settings API supports enabling all protocols by setting the field to null, e.g.:

curl -X PUT --header "PRIVATE-TOKEN: $GITLAB_ACCESS_TOKEN" http://localhost:8080/api/v4/application/settings --header 'Content-Type: application/json' --data  '{"enabled_git_access_protocol": null}'

However, that is currently not possible, because the json tag contains omitempty and there is no special marshaller for it.

There are currently provider users facing this issue.

[theoriginalstove]

I could be wrong here, but I feel like this is fairly simple to change by removing the omitempty tag for this field.
https://github.com/xanzy/go-gitlab/blob/master/settings.go#L521

[svanharmelen]

If you do that, you will need to actively set the field every time you want to change a setting. Even if you do not want to change the enabled_git_access_protocol but only some other setting. I think that would be very unexpected behavior for users of this lib.

[theoriginalstove]

Hmm that does make this a bit tricky to fix. I can see that being an annoying behavior as well if all of a sudden users need to set ssh or http if it was reverted to nil from removing the omitempty tag, and now their project allows both protocols.

Thoughts on a special marshaller for the UpdateSettings struct and if the value == "nil", then marshal enabled_git_access_protocol into null. Or if you have other ideas on how to fix this, I'd be happy to get it done.