[Samba] winbind on DC : how use gidNumber instead of primaryGroupID as user's primary group

[Prunk Dump]

Hi Samba Team !

My Samba AD DC server run an NFSv4 server so I need correct RFC2307 id
mapping between the server and the clients.

On the client side it's very easy with the new smb.conf options :

idmap config SAMDOM:unix_nss_info = yes
idmap config SAMDOM:unix_primary_group = yes

But on the server side winbind use the gidNumber of the group
corresponding to the user's primaryGroupID. Not the gidNumber
directly.

So all my users have their primary group set to "Domain Users" as I
have set the "Domain Users" gidNumber as say in the documentation.

How can I change this behavior ? On my NFSv4 shares all the files are
owned by the "Domain Users" group instead of the correct user primary
group.

Thanks for help !

Baptiste.