Merge remote-tracking branch 'origin/3.0' into 3.0
diff --git a/registry/polaris/core.go b/registry/polaris/core.go
index e87fac7..7e9f304 100644
--- a/registry/polaris/core.go
+++ b/registry/polaris/core.go
@@ -32,13 +32,13 @@
 	"dubbo.apache.org/dubbo-go/v3/remoting"
 )
 
-type subscriber func(remoting.EventType, []model.Instance)
+type item func(remoting.EventType, []model.Instance)
 
 type PolarisServiceWatcher struct {
 	consumer       api.ConsumerAPI
 	subscribeParam *api.WatchServiceRequest
 	lock           *sync.RWMutex
-	subscribers    []subscriber
+	subscribers    []item
 	execOnce       *sync.Once
 }
 
@@ -48,7 +48,7 @@
 		subscribeParam: param,
 		consumer:       consumer,
 		lock:           &sync.RWMutex{},
-		subscribers:    make([]subscriber, 0),
+		subscribers:    make([]item, 0),
 		execOnce:       &sync.Once{},
 	}
 	return watcher, nil
diff --git a/registry/polaris/core_test.go b/registry/polaris/core_test.go
index 0e806a3..26a573c 100644
--- a/registry/polaris/core_test.go
+++ b/registry/polaris/core_test.go
@@ -17,11 +17,15 @@
 )
 
 func TestPolarisServiceWatcher_AddSubscriber(t *testing.T) {
+	var (
+		newParam    api.WatchServiceRequest
+		newConsumer api.ConsumerAPI
+	)
 	type fields struct {
 		consumer       api.ConsumerAPI
 		subscribeParam *api.WatchServiceRequest
 		lock           *sync.RWMutex
-		subscribers    []subscriber
+		subscribers    []item
 		execOnce       *sync.Once
 	}
 	type args struct {
@@ -38,7 +42,7 @@
 				subscribeParam: &newParam,
 				consumer:       newConsumer,
 				lock:           &sync.RWMutex{},
-				subscribers:    make([]subscriber, 0),
+				subscribers:    make([]item, 0),
 				execOnce:       &sync.Once{},
 			}
 			assert.Empty(t, watcher)
diff --git a/registry/polaris/registry.go b/registry/polaris/registry.go
index 210c0da..255acdb 100644
--- a/registry/polaris/registry.go
+++ b/registry/polaris/registry.go
@@ -150,8 +150,11 @@
 
 // Subscribe returns nil if subscribing registry successfully. If not returns an error.
 func (pr *polarisRegistry) Subscribe(url *common.URL, notifyListener registry.NotifyListener) error {
-	var newParam api.WatchServiceRequest
-	var newConsumer api.ConsumerAPI
+	var (
+		newParam    api.WatchServiceRequest
+		newConsumer api.ConsumerAPI
+	)
+
 	role, _ := strconv.Atoi(url.GetParam(constant.RegistryRoleKey, ""))
 	if role != common.CONSUMER {
 		return nil