use const v1.ProtocolTCP replace of string TCP

test/e2e/framework/framework.go

@@ -548,7 +548,7 @@ func (f *Framework) CreateServiceForSimpleApp(contPort, svcPort int, appName str
 			return nil
 		} else {
 			return []v1.ServicePort{{
-				Protocol:   "TCP",
+				Protocol:   v1.ProtocolTCP,
 				Port:       int32(svcPort),
 				TargetPort: intstr.FromInt(contPort),
 			}}

test/e2e/framework/service_util.go

@@ -254,7 +254,7 @@ func (j *ServiceTestJig) CreateOnlyLocalNodePortService(namespace, serviceName s
 	svc := j.CreateTCPServiceOrFail(namespace, func(svc *v1.Service) {
 		svc.Spec.Type = v1.ServiceTypeNodePort
 		svc.Spec.ExternalTrafficPolicy = v1.ServiceExternalTrafficPolicyTypeLocal
-		svc.Spec.Ports = []v1.ServicePort{{Protocol: "TCP", Port: 80}}
+		svc.Spec.Ports = []v1.ServicePort{{Protocol: v1.ProtocolTCP, Port: 80}}
 	})
 
 	if createPod {
@@ -1414,7 +1414,7 @@ func CreateServiceSpec(serviceName, externalName string, isHeadless bool, select
 		headlessService.Spec.ExternalName = externalName
 	} else {
 		headlessService.Spec.Ports = []v1.ServicePort{
-			{Port: 80, Name: "http", Protocol: "TCP"},
+			{Port: 80, Name: "http", Protocol: v1.ProtocolTCP},
 		}
 	}
 	if isHeadless {

test/e2e/framework/statefulset_utils.go

@@ -64,7 +64,7 @@ func CreateStatefulSetService(name string, labels map[string]string) *v1.Service
 		},
 	}
 	headlessService.Spec.Ports = []v1.ServicePort{
-		{Port: 80, Name: "http", Protocol: "TCP"},
+		{Port: 80, Name: "http", Protocol: v1.ProtocolTCP},
 	}
 	headlessService.Spec.ClusterIP = "None"
 	return headlessService