diff --git a/vendor/google.golang.org/protobuf/internal/encoding/defval/default.go b/vendor/google.golang.org/protobuf/internal/encoding/defval/default.go
new file mode 100644
index 0000000..fdd9b13
--- /dev/null
+++ b/vendor/google.golang.org/protobuf/internal/encoding/defval/default.go
@@ -0,0 +1,213 @@
+// 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 defval marshals and unmarshals textual forms of default values.
+//
+// This package handles both the form historically used in Go struct field tags
+// and also the form used by google.protobuf.FieldDescriptorProto.default_value
+// since they differ in superficial ways.
+package defval
+
+import (
+	"fmt"
+	"math"
+	"strconv"
+
+	ptext "google.golang.org/protobuf/internal/encoding/text"
+	errors "google.golang.org/protobuf/internal/errors"
+	pref "google.golang.org/protobuf/reflect/protoreflect"
+)
+
+// Format is the serialization format used to represent the default value.
+type Format int
+
+const (
+	_ Format = iota
+
+	// Descriptor uses the serialization format that protoc uses with the
+	// google.protobuf.FieldDescriptorProto.default_value field.
+	Descriptor
+
+	// GoTag uses the historical serialization format in Go struct field tags.
+	GoTag
+)
+
+// Unmarshal deserializes the default string s according to the given kind k.
+// When k is an enum, a list of enum value descriptors must be provided.
+func Unmarshal(s string, k pref.Kind, evs pref.EnumValueDescriptors, f Format) (pref.Value, pref.EnumValueDescriptor, error) {
+	switch k {
+	case pref.BoolKind:
+		if f == GoTag {
+			switch s {
+			case "1":
+				return pref.ValueOfBool(true), nil, nil
+			case "0":
+				return pref.ValueOfBool(false), nil, nil
+			}
+		} else {
+			switch s {
+			case "true":
+				return pref.ValueOfBool(true), nil, nil
+			case "false":
+				return pref.ValueOfBool(false), nil, nil
+			}
+		}
+	case pref.EnumKind:
+		if f == GoTag {
+			// Go tags use the numeric form of the enum value.
+			if n, err := strconv.ParseInt(s, 10, 32); err == nil {
+				if ev := evs.ByNumber(pref.EnumNumber(n)); ev != nil {
+					return pref.ValueOfEnum(ev.Number()), ev, nil
+				}
+			}
+		} else {
+			// Descriptor default_value use the enum identifier.
+			ev := evs.ByName(pref.Name(s))
+			if ev != nil {
+				return pref.ValueOfEnum(ev.Number()), ev, nil
+			}
+		}
+	case pref.Int32Kind, pref.Sint32Kind, pref.Sfixed32Kind:
+		if v, err := strconv.ParseInt(s, 10, 32); err == nil {
+			return pref.ValueOfInt32(int32(v)), nil, nil
+		}
+	case pref.Int64Kind, pref.Sint64Kind, pref.Sfixed64Kind:
+		if v, err := strconv.ParseInt(s, 10, 64); err == nil {
+			return pref.ValueOfInt64(int64(v)), nil, nil
+		}
+	case pref.Uint32Kind, pref.Fixed32Kind:
+		if v, err := strconv.ParseUint(s, 10, 32); err == nil {
+			return pref.ValueOfUint32(uint32(v)), nil, nil
+		}
+	case pref.Uint64Kind, pref.Fixed64Kind:
+		if v, err := strconv.ParseUint(s, 10, 64); err == nil {
+			return pref.ValueOfUint64(uint64(v)), nil, nil
+		}
+	case pref.FloatKind, pref.DoubleKind:
+		var v float64
+		var err error
+		switch s {
+		case "-inf":
+			v = math.Inf(-1)
+		case "inf":
+			v = math.Inf(+1)
+		case "nan":
+			v = math.NaN()
+		default:
+			v, err = strconv.ParseFloat(s, 64)
+		}
+		if err == nil {
+			if k == pref.FloatKind {
+				return pref.ValueOfFloat32(float32(v)), nil, nil
+			} else {
+				return pref.ValueOfFloat64(float64(v)), nil, nil
+			}
+		}
+	case pref.StringKind:
+		// String values are already unescaped and can be used as is.
+		return pref.ValueOfString(s), nil, nil
+	case pref.BytesKind:
+		if b, ok := unmarshalBytes(s); ok {
+			return pref.ValueOfBytes(b), nil, nil
+		}
+	}
+	return pref.Value{}, nil, errors.New("could not parse value for %v: %q", k, s)
+}
+
+// Marshal serializes v as the default string according to the given kind k.
+// When specifying the Descriptor format for an enum kind, the associated
+// enum value descriptor must be provided.
+func Marshal(v pref.Value, ev pref.EnumValueDescriptor, k pref.Kind, f Format) (string, error) {
+	switch k {
+	case pref.BoolKind:
+		if f == GoTag {
+			if v.Bool() {
+				return "1", nil
+			} else {
+				return "0", nil
+			}
+		} else {
+			if v.Bool() {
+				return "true", nil
+			} else {
+				return "false", nil
+			}
+		}
+	case pref.EnumKind:
+		if f == GoTag {
+			return strconv.FormatInt(int64(v.Enum()), 10), nil
+		} else {
+			return string(ev.Name()), nil
+		}
+	case pref.Int32Kind, pref.Sint32Kind, pref.Sfixed32Kind, pref.Int64Kind, pref.Sint64Kind, pref.Sfixed64Kind:
+		return strconv.FormatInt(v.Int(), 10), nil
+	case pref.Uint32Kind, pref.Fixed32Kind, pref.Uint64Kind, pref.Fixed64Kind:
+		return strconv.FormatUint(v.Uint(), 10), nil
+	case pref.FloatKind, pref.DoubleKind:
+		f := v.Float()
+		switch {
+		case math.IsInf(f, -1):
+			return "-inf", nil
+		case math.IsInf(f, +1):
+			return "inf", nil
+		case math.IsNaN(f):
+			return "nan", nil
+		default:
+			if k == pref.FloatKind {
+				return strconv.FormatFloat(f, 'g', -1, 32), nil
+			} else {
+				return strconv.FormatFloat(f, 'g', -1, 64), nil
+			}
+		}
+	case pref.StringKind:
+		// String values are serialized as is without any escaping.
+		return v.String(), nil
+	case pref.BytesKind:
+		if s, ok := marshalBytes(v.Bytes()); ok {
+			return s, nil
+		}
+	}
+	return "", errors.New("could not format value for %v: %v", k, v)
+}
+
+// unmarshalBytes deserializes bytes by applying C unescaping.
+func unmarshalBytes(s string) ([]byte, bool) {
+	// Bytes values use the same escaping as the text format,
+	// however they lack the surrounding double quotes.
+	v, err := ptext.UnmarshalString(`"` + s + `"`)
+	if err != nil {
+		return nil, false
+	}
+	return []byte(v), true
+}
+
+// marshalBytes serializes bytes by using C escaping.
+// To match the exact output of protoc, this is identical to the
+// CEscape function in strutil.cc of the protoc source code.
+func marshalBytes(b []byte) (string, bool) {
+	var s []byte
+	for _, c := range b {
+		switch c {
+		case '\n':
+			s = append(s, `\n`...)
+		case '\r':
+			s = append(s, `\r`...)
+		case '\t':
+			s = append(s, `\t`...)
+		case '"':
+			s = append(s, `\"`...)
+		case '\'':
+			s = append(s, `\'`...)
+		case '\\':
+			s = append(s, `\\`...)
+		default:
+			if printableASCII := c >= 0x20 && c <= 0x7e; printableASCII {
+				s = append(s, c)
+			} else {
+				s = append(s, fmt.Sprintf(`\%03o`, c)...)
+			}
+		}
+	}
+	return string(s), true
+}