You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: 20210914153600_issue_3194_update_permissions.rb
    path of file: ./repos/zammad/db/migrate
    
    the code of the file until where you have to start completion: # Copyright (C) 2012-2024 Zammad Foundation, https://zammad-foundation.org/

class Issue3194UpdatePermissions < ActiveRecord::Migration[6.0]
  def change
    # return if it's a new setup
    return 
    
  def change
    # return if it's a new setup
    return if !Setting.exists?(name: 'system_init_done')

    settings = %w[
      ticket_subject_size
      ticket_subject_re
      ticket_subject_fwd
      ticket_define_email_from
      ticket_define_email_from_separator
      postmaster_max_size
      postmaster_follow_up_search_in
      postmaster_sender_based_on_reply_to
      postmaster_sender_is_agent_search_for_customer
      postmaster_send_reject_if_mail_too_large
      notification_sender
      send_no_auto_response_reg_exp
    ]

    Setting.where(name: settings).each do |setting|
      setting.preferences[:permission] += ['admin.channel_google', 'admin.channel_microsoft365']
      setting.save
    end
  end