diff --git a/vendor/google.golang.org/protobuf/internal/mapsort/mapsort.go b/vendor/google.golang.org/protobuf/internal/mapsort/mapsort.go
new file mode 100644
index 0000000..a3de1cf
--- /dev/null
+++ b/vendor/google.golang.org/protobuf/internal/mapsort/mapsort.go
@@ -0,0 +1,43 @@
+// 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 mapsort provides sorted access to maps.
+package mapsort
+
+import (
+	"sort"
+
+	"google.golang.org/protobuf/reflect/protoreflect"
+)
+
+// Range iterates over every map entry in sorted key order,
+// calling f for each key and value encountered.
+func Range(mapv protoreflect.Map, keyKind protoreflect.Kind, f func(protoreflect.MapKey, protoreflect.Value) bool) {
+	var keys []protoreflect.MapKey
+	mapv.Range(func(key protoreflect.MapKey, _ protoreflect.Value) bool {
+		keys = append(keys, key)
+		return true
+	})
+	sort.Slice(keys, func(i, j int) bool {
+		switch keyKind {
+		case protoreflect.BoolKind:
+			return !keys[i].Bool() && keys[j].Bool()
+		case protoreflect.Int32Kind, protoreflect.Sint32Kind, protoreflect.Sfixed32Kind,
+			protoreflect.Int64Kind, protoreflect.Sint64Kind, protoreflect.Sfixed64Kind:
+			return keys[i].Int() < keys[j].Int()
+		case protoreflect.Uint32Kind, protoreflect.Fixed32Kind,
+			protoreflect.Uint64Kind, protoreflect.Fixed64Kind:
+			return keys[i].Uint() < keys[j].Uint()
+		case protoreflect.StringKind:
+			return keys[i].String() < keys[j].String()
+		default:
+			panic("invalid kind: " + keyKind.String())
+		}
+	})
+	for _, key := range keys {
+		if !f(key, mapv.Get(key)) {
+			break
+		}
+	}
+}