{
// required
meeting_user_id: Id;
motion_id: Id;
}
Creates a new submitter. The user and motion must belong to the same meeting. The fields
meeting_user_id
and motion_id
are unique together, so it must be checked that the user doesn't
already exists as a submitter. The weight
must be set to the maximum of all submitters of the
motion plus 1.
The request user needs can_manage_metadata
.