Why can't ApisixRouteHTTPBackend cross-namespace?

[Tanc010]

Description

// ApisixRouteHTTPBackend represents an HTTP backend (a Kubernetes Service).
type ApisixRouteHTTPBackend struct {
// The name (short) of the service, note cross namespace is forbidden,
// so be sure the ApisixRoute and Service are in the same namespace.
ServiceName string json:"serviceName" yaml:"serviceName"
// The service port, could be the name or the port number.
ServicePort intstr.IntOrString json:"servicePort" yaml:"servicePort"
// The resolve granularity, can be "endpoints" or "service",
// when set to "endpoints", the pod ips will be used; other
// wise, the service ClusterIP or ExternalIP will be used,
// default is endpoints.
ResolveGranularity string json:"resolveGranularity,omitempty" yaml:"resolveGranularity,omitempty"
// Weight of this backend.
Weight *int json:"weight" yaml:"weight"
// Subset specifies a subset for the target Service. The subset should be pre-defined
// in ApisixUpstream about this service.
Subset string json:"subset,omitempty" yaml:"subset,omitempty"
}

[Tanc010]

Repeated problem