diff --git a/vendor/google.golang.org/protobuf/internal/impl/legacy_file.go b/vendor/google.golang.org/protobuf/internal/impl/legacy_file.go
new file mode 100644
index 0000000..9ab0910
--- /dev/null
+++ b/vendor/google.golang.org/protobuf/internal/impl/legacy_file.go
@@ -0,0 +1,81 @@
+// Copyright 2018 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 (
+	"bytes"
+	"compress/gzip"
+	"io/ioutil"
+	"sync"
+
+	"google.golang.org/protobuf/internal/filedesc"
+	"google.golang.org/protobuf/reflect/protoreflect"
+	"google.golang.org/protobuf/reflect/protoregistry"
+)
+
+// Every enum and message type generated by protoc-gen-go since commit 2fc053c5
+// on February 25th, 2016 has had a method to get the raw descriptor.
+// Types that were not generated by protoc-gen-go or were generated prior
+// to that version are not supported.
+//
+// The []byte returned is the encoded form of a FileDescriptorProto message
+// compressed using GZIP. The []int is the path from the top-level file
+// to the specific message or enum declaration.
+type (
+	enumV1 interface {
+		EnumDescriptor() ([]byte, []int)
+	}
+	messageV1 interface {
+		Descriptor() ([]byte, []int)
+	}
+)
+
+var legacyFileDescCache sync.Map // map[*byte]protoreflect.FileDescriptor
+
+// legacyLoadFileDesc unmarshals b as a compressed FileDescriptorProto message.
+//
+// This assumes that b is immutable and that b does not refer to part of a
+// concatenated series of GZIP files (which would require shenanigans that
+// rely on the concatenation properties of both protobufs and GZIP).
+// File descriptors generated by protoc-gen-go do not rely on that property.
+func legacyLoadFileDesc(b []byte) protoreflect.FileDescriptor {
+	// Fast-path: check whether we already have a cached file descriptor.
+	if fd, ok := legacyFileDescCache.Load(&b[0]); ok {
+		return fd.(protoreflect.FileDescriptor)
+	}
+
+	// Slow-path: decompress and unmarshal the file descriptor proto.
+	zr, err := gzip.NewReader(bytes.NewReader(b))
+	if err != nil {
+		panic(err)
+	}
+	b2, err := ioutil.ReadAll(zr)
+	if err != nil {
+		panic(err)
+	}
+
+	fd := filedesc.Builder{
+		RawDescriptor: b2,
+		FileRegistry:  resolverOnly{protoregistry.GlobalFiles}, // do not register back to global registry
+	}.Build().File
+	if fd, ok := legacyFileDescCache.LoadOrStore(&b[0], fd); ok {
+		return fd.(protoreflect.FileDescriptor)
+	}
+	return fd
+}
+
+type resolverOnly struct {
+	reg *protoregistry.Files
+}
+
+func (r resolverOnly) FindFileByPath(path string) (protoreflect.FileDescriptor, error) {
+	return r.reg.FindFileByPath(path)
+}
+func (r resolverOnly) FindDescriptorByName(name protoreflect.FullName) (protoreflect.Descriptor, error) {
+	return r.reg.FindDescriptorByName(name)
+}
+func (resolverOnly) RegisterFile(protoreflect.FileDescriptor) error {
+	return nil
+}