code: def alert_add_entity(entity_id, condition_id, entity_type = 'Server')
        nr_api.put do |req|
          req.url url('alerts_entity_conditions', entity_id)
          req.params['entity_type'] = entity_type
          req.params['condition_id'] = condition_id
        end
      end
docs: => Add an Entitity to an Existing Alert Policy