diff --git a/vendor/google.golang.org/protobuf/internal/impl/codec_reflect.go b/vendor/google.golang.org/protobuf/internal/impl/codec_reflect.go
new file mode 100644
index 0000000..86f7dc3
--- /dev/null
+++ b/vendor/google.golang.org/protobuf/internal/impl/codec_reflect.go
@@ -0,0 +1,209 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build purego appengine
+
+package impl
+
+import (
+	"reflect"
+
+	"google.golang.org/protobuf/encoding/protowire"
+)
+
+func sizeEnum(p pointer, f *coderFieldInfo, _ marshalOptions) (size int) {
+	v := p.v.Elem().Int()
+	return f.tagsize + protowire.SizeVarint(uint64(v))
+}
+
+func appendEnum(b []byte, p pointer, f *coderFieldInfo, opts marshalOptions) ([]byte, error) {
+	v := p.v.Elem().Int()
+	b = protowire.AppendVarint(b, f.wiretag)
+	b = protowire.AppendVarint(b, uint64(v))
+	return b, nil
+}
+
+func consumeEnum(b []byte, p pointer, wtyp protowire.Type, f *coderFieldInfo, _ unmarshalOptions) (out unmarshalOutput, err error) {
+	if wtyp != protowire.VarintType {
+		return out, errUnknown
+	}
+	v, n := protowire.ConsumeVarint(b)
+	if n < 0 {
+		return out, protowire.ParseError(n)
+	}
+	p.v.Elem().SetInt(int64(v))
+	out.n = n
+	return out, nil
+}
+
+func mergeEnum(dst, src pointer, _ *coderFieldInfo, _ mergeOptions) {
+	dst.v.Elem().Set(src.v.Elem())
+}
+
+var coderEnum = pointerCoderFuncs{
+	size:      sizeEnum,
+	marshal:   appendEnum,
+	unmarshal: consumeEnum,
+	merge:     mergeEnum,
+}
+
+func sizeEnumNoZero(p pointer, f *coderFieldInfo, opts marshalOptions) (size int) {
+	if p.v.Elem().Int() == 0 {
+		return 0
+	}
+	return sizeEnum(p, f, opts)
+}
+
+func appendEnumNoZero(b []byte, p pointer, f *coderFieldInfo, opts marshalOptions) ([]byte, error) {
+	if p.v.Elem().Int() == 0 {
+		return b, nil
+	}
+	return appendEnum(b, p, f, opts)
+}
+
+func mergeEnumNoZero(dst, src pointer, _ *coderFieldInfo, _ mergeOptions) {
+	if src.v.Elem().Int() != 0 {
+		dst.v.Elem().Set(src.v.Elem())
+	}
+}
+
+var coderEnumNoZero = pointerCoderFuncs{
+	size:      sizeEnumNoZero,
+	marshal:   appendEnumNoZero,
+	unmarshal: consumeEnum,
+	merge:     mergeEnumNoZero,
+}
+
+func sizeEnumPtr(p pointer, f *coderFieldInfo, opts marshalOptions) (size int) {
+	return sizeEnum(pointer{p.v.Elem()}, f, opts)
+}
+
+func appendEnumPtr(b []byte, p pointer, f *coderFieldInfo, opts marshalOptions) ([]byte, error) {
+	return appendEnum(b, pointer{p.v.Elem()}, f, opts)
+}
+
+func consumeEnumPtr(b []byte, p pointer, wtyp protowire.Type, f *coderFieldInfo, opts unmarshalOptions) (out unmarshalOutput, err error) {
+	if wtyp != protowire.VarintType {
+		return out, errUnknown
+	}
+	if p.v.Elem().IsNil() {
+		p.v.Elem().Set(reflect.New(p.v.Elem().Type().Elem()))
+	}
+	return consumeEnum(b, pointer{p.v.Elem()}, wtyp, f, opts)
+}
+
+func mergeEnumPtr(dst, src pointer, _ *coderFieldInfo, _ mergeOptions) {
+	if !src.v.Elem().IsNil() {
+		v := reflect.New(dst.v.Type().Elem().Elem())
+		v.Elem().Set(src.v.Elem().Elem())
+		dst.v.Elem().Set(v)
+	}
+}
+
+var coderEnumPtr = pointerCoderFuncs{
+	size:      sizeEnumPtr,
+	marshal:   appendEnumPtr,
+	unmarshal: consumeEnumPtr,
+	merge:     mergeEnumPtr,
+}
+
+func sizeEnumSlice(p pointer, f *coderFieldInfo, opts marshalOptions) (size int) {
+	s := p.v.Elem()
+	for i, llen := 0, s.Len(); i < llen; i++ {
+		size += protowire.SizeVarint(uint64(s.Index(i).Int())) + f.tagsize
+	}
+	return size
+}
+
+func appendEnumSlice(b []byte, p pointer, f *coderFieldInfo, opts marshalOptions) ([]byte, error) {
+	s := p.v.Elem()
+	for i, llen := 0, s.Len(); i < llen; i++ {
+		b = protowire.AppendVarint(b, f.wiretag)
+		b = protowire.AppendVarint(b, uint64(s.Index(i).Int()))
+	}
+	return b, nil
+}
+
+func consumeEnumSlice(b []byte, p pointer, wtyp protowire.Type, f *coderFieldInfo, opts unmarshalOptions) (out unmarshalOutput, err error) {
+	s := p.v.Elem()
+	if wtyp == protowire.BytesType {
+		b, n := protowire.ConsumeBytes(b)
+		if n < 0 {
+			return out, protowire.ParseError(n)
+		}
+		for len(b) > 0 {
+			v, n := protowire.ConsumeVarint(b)
+			if n < 0 {
+				return out, protowire.ParseError(n)
+			}
+			rv := reflect.New(s.Type().Elem()).Elem()
+			rv.SetInt(int64(v))
+			s.Set(reflect.Append(s, rv))
+			b = b[n:]
+		}
+		out.n = n
+		return out, nil
+	}
+	if wtyp != protowire.VarintType {
+		return out, errUnknown
+	}
+	v, n := protowire.ConsumeVarint(b)
+	if n < 0 {
+		return out, protowire.ParseError(n)
+	}
+	rv := reflect.New(s.Type().Elem()).Elem()
+	rv.SetInt(int64(v))
+	s.Set(reflect.Append(s, rv))
+	out.n = n
+	return out, nil
+}
+
+func mergeEnumSlice(dst, src pointer, _ *coderFieldInfo, _ mergeOptions) {
+	dst.v.Elem().Set(reflect.AppendSlice(dst.v.Elem(), src.v.Elem()))
+}
+
+var coderEnumSlice = pointerCoderFuncs{
+	size:      sizeEnumSlice,
+	marshal:   appendEnumSlice,
+	unmarshal: consumeEnumSlice,
+	merge:     mergeEnumSlice,
+}
+
+func sizeEnumPackedSlice(p pointer, f *coderFieldInfo, opts marshalOptions) (size int) {
+	s := p.v.Elem()
+	llen := s.Len()
+	if llen == 0 {
+		return 0
+	}
+	n := 0
+	for i := 0; i < llen; i++ {
+		n += protowire.SizeVarint(uint64(s.Index(i).Int()))
+	}
+	return f.tagsize + protowire.SizeBytes(n)
+}
+
+func appendEnumPackedSlice(b []byte, p pointer, f *coderFieldInfo, opts marshalOptions) ([]byte, error) {
+	s := p.v.Elem()
+	llen := s.Len()
+	if llen == 0 {
+		return b, nil
+	}
+	b = protowire.AppendVarint(b, f.wiretag)
+	n := 0
+	for i := 0; i < llen; i++ {
+		n += protowire.SizeVarint(uint64(s.Index(i).Int()))
+	}
+	b = protowire.AppendVarint(b, uint64(n))
+	for i := 0; i < llen; i++ {
+		b = protowire.AppendVarint(b, uint64(s.Index(i).Int()))
+	}
+	return b, nil
+}
+
+var coderEnumPackedSlice = pointerCoderFuncs{
+	size:      sizeEnumPackedSlice,
+	marshal:   appendEnumPackedSlice,
+	unmarshal: consumeEnumSlice,
+	merge:     mergeEnumSlice,
+}