Okay.
I’ve found the solution.
I have to call set_ruleset with ruleset_name “host_contactgroups” and ruleset parameter with an array with this structure:
"<FOLDER_NAME>": [
{
"value": "<CONTACT_GROUP>",
"condition": {},
"options": {
"description": "<DESCRIPTION>"
}
}
],
The bad part is I have to send always ALL rules because this calls override completely. Is not an ADD but a TRUNCATE → INSERT.