Fortiauthenticator API : create localuser expires_at

Hi,

I have a problem with the RESTAPI to create a localuser on my Fortiauthenticator.

When i use the expires_at field, i get automatically an error :

Cannot add local user "toto" (Response: HTTP 400), Error: b'{"localusers": {"expires_at": ["Invalid time format. Time should be formatted using ISO-8601 (e.g. 2015-02-17T15:42:50.972335-08:00). If timezone is not given, time is assumed to be in UTC."]}}'

I'd tried with many format (with and without timezone, miliseconds), i also tried with the example... Nothing at all.