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: service_stack.rb
    path of file: ./repos/barcelona/app/models/backend/ecs/v2
    
    the code of the file until where you have to start completion: module Backend::Ecs::V2
  class ServiceStack < CloudFormation::Stack
    class Builder < CloudFormation::Builder
      def build_resources
        deps = []
        if use_alb?
          deps = ['LBListenerRuleHTTP']

          if listener&.endpoint&.https_listener_id&.present?
            deps << 'LBListenerRuleHTTPS'
          end
        end

        add_resource("AWS::ECS::Service",
    
      def listener
        # For now we don't support multiple listeners
        service.listeners.first
      end

      def use_tcp_load_balancer?
        # Using port_mappings or hosts requires ELB run in TCP mode which is supported
        # only by Classic ELB. Only in the case above we use Classic ELB
        !use_alb? && (service.port_mappings.present? || service.hosts.present?)
      end

      def use_alb?
        listener.present?
      end
    end