diff --git a/demo_test/vendor/google.golang.org/protobuf/internal/impl/legacy_export.go b/demo_test/vendor/google.golang.org/protobuf/internal/impl/legacy_export.go
new file mode 100644
index 0000000..94f4572
--- /dev/null
+++ b/demo_test/vendor/google.golang.org/protobuf/internal/impl/legacy_export.go
@@ -0,0 +1,104 @@
+// 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.
+
+package impl
+
+import (
+	"encoding/binary"
+	"encoding/json"
+	"fmt"
+	"hash/crc32"
+	"math"
+	"reflect"
+
+	"google.golang.org/protobuf/internal/errors"
+	pref "google.golang.org/protobuf/reflect/protoreflect"
+	"google.golang.org/protobuf/reflect/protoregistry"
+	piface "google.golang.org/protobuf/runtime/protoiface"
+)
+
+// These functions exist to support exported APIs in generated protobufs.
+// While these are deprecated, they cannot be removed for compatibility reasons.
+
+// LegacyEnumName returns the name of enums used in legacy code.
+func (Export) LegacyEnumName(ed pref.EnumDescriptor) string {
+	return legacyEnumName(ed)
+}
+
+// LegacyMessageTypeOf returns the protoreflect.MessageType for m,
+// with name used as the message name if necessary.
+func (Export) LegacyMessageTypeOf(m piface.MessageV1, name pref.FullName) pref.MessageType {
+	if mv := (Export{}).protoMessageV2Of(m); mv != nil {
+		return mv.ProtoReflect().Type()
+	}
+	return legacyLoadMessageInfo(reflect.TypeOf(m), name)
+}
+
+// UnmarshalJSONEnum unmarshals an enum from a JSON-encoded input.
+// The input can either be a string representing the enum value by name,
+// or a number representing the enum number itself.
+func (Export) UnmarshalJSONEnum(ed pref.EnumDescriptor, b []byte) (pref.EnumNumber, error) {
+	if b[0] == '"' {
+		var name pref.Name
+		if err := json.Unmarshal(b, &name); err != nil {
+			return 0, errors.New("invalid input for enum %v: %s", ed.FullName(), b)
+		}
+		ev := ed.Values().ByName(name)
+		if ev == nil {
+			return 0, errors.New("invalid value for enum %v: %s", ed.FullName(), name)
+		}
+		return ev.Number(), nil
+	} else {
+		var num pref.EnumNumber
+		if err := json.Unmarshal(b, &num); err != nil {
+			return 0, errors.New("invalid input for enum %v: %s", ed.FullName(), b)
+		}
+		return num, nil
+	}
+}
+
+// CompressGZIP compresses the input as a GZIP-encoded file.
+// The current implementation does no compression.
+func (Export) CompressGZIP(in []byte) (out []byte) {
+	// RFC 1952, section 2.3.1.
+	var gzipHeader = [10]byte{0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff}
+
+	// RFC 1951, section 3.2.4.
+	var blockHeader [5]byte
+	const maxBlockSize = math.MaxUint16
+	numBlocks := 1 + len(in)/maxBlockSize
+
+	// RFC 1952, section 2.3.1.
+	var gzipFooter [8]byte
+	binary.LittleEndian.PutUint32(gzipFooter[0:4], crc32.ChecksumIEEE(in))
+	binary.LittleEndian.PutUint32(gzipFooter[4:8], uint32(len(in)))
+
+	// Encode the input without compression using raw DEFLATE blocks.
+	out = make([]byte, 0, len(gzipHeader)+len(blockHeader)*numBlocks+len(in)+len(gzipFooter))
+	out = append(out, gzipHeader[:]...)
+	for blockHeader[0] == 0 {
+		blockSize := maxBlockSize
+		if blockSize > len(in) {
+			blockHeader[0] = 0x01 // final bit per RFC 1951, section 3.2.3.
+			blockSize = len(in)
+		}
+		binary.LittleEndian.PutUint16(blockHeader[1:3], uint16(blockSize)^0x0000)
+		binary.LittleEndian.PutUint16(blockHeader[3:5], uint16(blockSize)^0xffff)
+		out = append(out, blockHeader[:]...)
+		out = append(out, in[:blockSize]...)
+		in = in[blockSize:]
+	}
+	out = append(out, gzipFooter[:]...)
+	return out
+}
+
+// WeakNil returns a typed nil pointer to a concrete message.
+// It panics if the message is not linked into the binary.
+func (Export) WeakNil(s pref.FullName) piface.MessageV1 {
+	mt, err := protoregistry.GlobalTypes.FindMessageByName(s)
+	if err != nil {
+		panic(fmt.Sprintf("weak message %v is not linked in", s))
+	}
+	return mt.Zero().Interface().(piface.MessageV1)
+}