With Gateway API enabled, why adding 8000 to the Listener port number is needed? about contour HOT 3 OPEN

func (p *ListenerProcessor) Run(dag *DAG, cache *KubernetesCache) {
	if cache.gateway != nil {
		dag.HasDynamicListeners = true

		for _, port := range gatewayapi.ValidateListeners(cache.gateway.Spec.Listeners).Ports {
			address := p.HTTPAddress
			if port.Protocol == "https" {
				address = p.HTTPSAddress
			}
			dag.Listeners[port.Name] = &Listener{
				Name:             port.Name,
				Protocol:         port.Protocol,
				Address:          address,
				Port:             int(port.ContainerPort),
				EnableWebsockets: true,
				vhostsByName:     map[string]*VirtualHost{},
				svhostsByName:    map[string]*SecureVirtualHost{},
			}
		}
	} else {
		dag.Listeners[HTTP_LISTENER_NAME] = &Listener{
			Name:            HTTP_LISTENER_NAME,
			Protocol:        "http",
			Address:         p.HTTPAddress,
			Port:            intOrDefault(p.HTTPPort, 8080),
			RouteConfigName: "ingress_http",
			vhostsByName:    map[string]*VirtualHost{},
		}

		dag.Listeners[HTTPS_LISTENER_NAME] = &Listener{
			Name:                        HTTPS_LISTENER_NAME,
			Protocol:                    "https",
			Address:                     p.HTTPSAddress,
			Port:                        intOrDefault(p.HTTPSPort, 8443),
			RouteConfigName:             "https",
			FallbackCertRouteConfigName: "ingress_fallbackcert",
			svhostsByName:               map[string]*SecureVirtualHost{},
		}
	}
}