# File lib/oauth2/access_token.rb, line 82
    def refresh!(params = {})
      raise('A refresh_token is not available') unless refresh_token
      params[:grant_type] = 'refresh_token'
      params[:refresh_token] = refresh_token
      new_token = @client.get_token(params)
      new_token.options = options
      new_token.refresh_token = refresh_token unless new_token.refresh_token
      new_token
    end