use istio client-go library instead of knative (#1661)

use istio client-go library instead of knative
bump kubernetes dependency version
change code coverage to codecov

vendor/k8s.io/kube-openapi/pkg/common/common.go

@@ -24,6 +24,12 @@ import (
 	"github.com/go-openapi/spec"
 )
 
+const (
+	// TODO: Make this configurable.
+	ExtensionPrefix = "x-kubernetes-"
+	ExtensionV2Schema = ExtensionPrefix + "v2-schema"
+)
+
 // OpenAPIDefinition describes single type. Normally these definitions are auto-generated using gen-openapi.
 type OpenAPIDefinition struct {
 	Schema       spec.Schema
@@ -43,6 +49,10 @@ type OpenAPIDefinitionGetter interface {
 	OpenAPIDefinition() *OpenAPIDefinition
 }
 
+type OpenAPIV3DefinitionGetter interface {
+	OpenAPIV3Definition() *OpenAPIDefinition
+}
+
 type PathHandler interface {
 	Handle(path string, handler http.Handler)
 }
@@ -172,3 +182,11 @@ func EscapeJsonPointer(p string) string {
 	p = strings.Replace(p, "/", "~1", -1)
 	return p
 }
+
+func EmbedOpenAPIDefinitionIntoV2Extension(main OpenAPIDefinition, embedded OpenAPIDefinition) OpenAPIDefinition {
+	if main.Schema.Extensions == nil {
+		main.Schema.Extensions = make(map[string]interface{})
+	}
+	main.Schema.Extensions[ExtensionV2Schema] = embedded.Schema
+	return main
+}