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/github.com/gogo/protobuf/proto/table_marshal.go

@@ -389,8 +389,13 @@ func (u *marshalInfo) computeMarshalInfo() {
 	// get oneof implementers
 	var oneofImplementers []interface{}
 	// gogo: isOneofMessage is needed for embedded oneof messages, without a marshaler and unmarshaler
-	if m, ok := reflect.Zero(reflect.PtrTo(t)).Interface().(oneofMessage); ok && isOneofMessage {
-		_, _, _, oneofImplementers = m.XXX_OneofFuncs()
+	if isOneofMessage {
+		switch m := reflect.Zero(reflect.PtrTo(t)).Interface().(type) {
+		case oneofFuncsIface:
+			_, _, _, oneofImplementers = m.XXX_OneofFuncs()
+		case oneofWrappersIface:
+			oneofImplementers = m.XXX_OneofWrappers()
+		}
 	}
 
 	// normal fields
@@ -491,7 +496,7 @@ func (fi *marshalFieldInfo) computeMarshalFieldInfo(f *reflect.StructField) {
 
 func (fi *marshalFieldInfo) computeOneofFieldInfo(f *reflect.StructField, oneofImplementers []interface{}) {
 	fi.field = toField(f)
-	fi.wiretag = 1<<31 - 1 // Use a large tag number, make oneofs sorted at the end. This tag will not appear on the wire.
+	fi.wiretag = math.MaxInt32 // Use a large tag number, make oneofs sorted at the end. This tag will not appear on the wire.
 	fi.isPointer = true
 	fi.sizer, fi.marshaler = makeOneOfMarshaler(fi, f)
 	fi.oneofElems = make(map[reflect.Type]*marshalElemInfo)
@@ -519,10 +524,6 @@ func (fi *marshalFieldInfo) computeOneofFieldInfo(f *reflect.StructField, oneofI
 	}
 }
 
-type oneofMessage interface {
-	XXX_OneofFuncs() (func(Message, *Buffer) error, func(Message, int, int, *Buffer) (bool, error), func(Message) int, []interface{})
-}
-
 // wiretype returns the wire encoding of the type.
 func wiretype(encoding string) uint64 {
 	switch encoding {