diff --git a/vendor/google.golang.org/protobuf/internal/encoding/json/encode.go b/vendor/google.golang.org/protobuf/internal/encoding/json/encode.go
new file mode 100644
index 0000000..fbdf348
--- /dev/null
+++ b/vendor/google.golang.org/protobuf/internal/encoding/json/encode.go
@@ -0,0 +1,276 @@
+// 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 json
+
+import (
+	"math"
+	"math/bits"
+	"strconv"
+	"strings"
+	"unicode/utf8"
+
+	"google.golang.org/protobuf/internal/detrand"
+	"google.golang.org/protobuf/internal/errors"
+)
+
+// kind represents an encoding type.
+type kind uint8
+
+const (
+	_ kind = (1 << iota) / 2
+	name
+	scalar
+	objectOpen
+	objectClose
+	arrayOpen
+	arrayClose
+)
+
+// Encoder provides methods to write out JSON constructs and values. The user is
+// responsible for producing valid sequences of JSON constructs and values.
+type Encoder struct {
+	indent   string
+	lastKind kind
+	indents  []byte
+	out      []byte
+}
+
+// NewEncoder returns an Encoder.
+//
+// If indent is a non-empty string, it causes every entry for an Array or Object
+// to be preceded by the indent and trailed by a newline.
+func NewEncoder(indent string) (*Encoder, error) {
+	e := &Encoder{}
+	if len(indent) > 0 {
+		if strings.Trim(indent, " \t") != "" {
+			return nil, errors.New("indent may only be composed of space or tab characters")
+		}
+		e.indent = indent
+	}
+	return e, nil
+}
+
+// Bytes returns the content of the written bytes.
+func (e *Encoder) Bytes() []byte {
+	return e.out
+}
+
+// WriteNull writes out the null value.
+func (e *Encoder) WriteNull() {
+	e.prepareNext(scalar)
+	e.out = append(e.out, "null"...)
+}
+
+// WriteBool writes out the given boolean value.
+func (e *Encoder) WriteBool(b bool) {
+	e.prepareNext(scalar)
+	if b {
+		e.out = append(e.out, "true"...)
+	} else {
+		e.out = append(e.out, "false"...)
+	}
+}
+
+// WriteString writes out the given string in JSON string value. Returns error
+// if input string contains invalid UTF-8.
+func (e *Encoder) WriteString(s string) error {
+	e.prepareNext(scalar)
+	var err error
+	if e.out, err = appendString(e.out, s); err != nil {
+		return err
+	}
+	return nil
+}
+
+// Sentinel error used for indicating invalid UTF-8.
+var errInvalidUTF8 = errors.New("invalid UTF-8")
+
+func appendString(out []byte, in string) ([]byte, error) {
+	out = append(out, '"')
+	i := indexNeedEscapeInString(in)
+	in, out = in[i:], append(out, in[:i]...)
+	for len(in) > 0 {
+		switch r, n := utf8.DecodeRuneInString(in); {
+		case r == utf8.RuneError && n == 1:
+			return out, errInvalidUTF8
+		case r < ' ' || r == '"' || r == '\\':
+			out = append(out, '\\')
+			switch r {
+			case '"', '\\':
+				out = append(out, byte(r))
+			case '\b':
+				out = append(out, 'b')
+			case '\f':
+				out = append(out, 'f')
+			case '\n':
+				out = append(out, 'n')
+			case '\r':
+				out = append(out, 'r')
+			case '\t':
+				out = append(out, 't')
+			default:
+				out = append(out, 'u')
+				out = append(out, "0000"[1+(bits.Len32(uint32(r))-1)/4:]...)
+				out = strconv.AppendUint(out, uint64(r), 16)
+			}
+			in = in[n:]
+		default:
+			i := indexNeedEscapeInString(in[n:])
+			in, out = in[n+i:], append(out, in[:n+i]...)
+		}
+	}
+	out = append(out, '"')
+	return out, nil
+}
+
+// indexNeedEscapeInString returns the index of the character that needs
+// escaping. If no characters need escaping, this returns the input length.
+func indexNeedEscapeInString(s string) int {
+	for i, r := range s {
+		if r < ' ' || r == '\\' || r == '"' || r == utf8.RuneError {
+			return i
+		}
+	}
+	return len(s)
+}
+
+// WriteFloat writes out the given float and bitSize in JSON number value.
+func (e *Encoder) WriteFloat(n float64, bitSize int) {
+	e.prepareNext(scalar)
+	e.out = appendFloat(e.out, n, bitSize)
+}
+
+// appendFloat formats given float in bitSize, and appends to the given []byte.
+func appendFloat(out []byte, n float64, bitSize int) []byte {
+	switch {
+	case math.IsNaN(n):
+		return append(out, `"NaN"`...)
+	case math.IsInf(n, +1):
+		return append(out, `"Infinity"`...)
+	case math.IsInf(n, -1):
+		return append(out, `"-Infinity"`...)
+	}
+
+	// JSON number formatting logic based on encoding/json.
+	// See floatEncoder.encode for reference.
+	fmt := byte('f')
+	if abs := math.Abs(n); abs != 0 {
+		if bitSize == 64 && (abs < 1e-6 || abs >= 1e21) ||
+			bitSize == 32 && (float32(abs) < 1e-6 || float32(abs) >= 1e21) {
+			fmt = 'e'
+		}
+	}
+	out = strconv.AppendFloat(out, n, fmt, -1, bitSize)
+	if fmt == 'e' {
+		n := len(out)
+		if n >= 4 && out[n-4] == 'e' && out[n-3] == '-' && out[n-2] == '0' {
+			out[n-2] = out[n-1]
+			out = out[:n-1]
+		}
+	}
+	return out
+}
+
+// WriteInt writes out the given signed integer in JSON number value.
+func (e *Encoder) WriteInt(n int64) {
+	e.prepareNext(scalar)
+	e.out = append(e.out, strconv.FormatInt(n, 10)...)
+}
+
+// WriteUint writes out the given unsigned integer in JSON number value.
+func (e *Encoder) WriteUint(n uint64) {
+	e.prepareNext(scalar)
+	e.out = append(e.out, strconv.FormatUint(n, 10)...)
+}
+
+// StartObject writes out the '{' symbol.
+func (e *Encoder) StartObject() {
+	e.prepareNext(objectOpen)
+	e.out = append(e.out, '{')
+}
+
+// EndObject writes out the '}' symbol.
+func (e *Encoder) EndObject() {
+	e.prepareNext(objectClose)
+	e.out = append(e.out, '}')
+}
+
+// WriteName writes out the given string in JSON string value and the name
+// separator ':'. Returns error if input string contains invalid UTF-8, which
+// should not be likely as protobuf field names should be valid.
+func (e *Encoder) WriteName(s string) error {
+	e.prepareNext(name)
+	var err error
+	// Append to output regardless of error.
+	e.out, err = appendString(e.out, s)
+	e.out = append(e.out, ':')
+	return err
+}
+
+// StartArray writes out the '[' symbol.
+func (e *Encoder) StartArray() {
+	e.prepareNext(arrayOpen)
+	e.out = append(e.out, '[')
+}
+
+// EndArray writes out the ']' symbol.
+func (e *Encoder) EndArray() {
+	e.prepareNext(arrayClose)
+	e.out = append(e.out, ']')
+}
+
+// prepareNext adds possible comma and indentation for the next value based
+// on last type and indent option. It also updates lastKind to next.
+func (e *Encoder) prepareNext(next kind) {
+	defer func() {
+		// Set lastKind to next.
+		e.lastKind = next
+	}()
+
+	if len(e.indent) == 0 {
+		// Need to add comma on the following condition.
+		if e.lastKind&(scalar|objectClose|arrayClose) != 0 &&
+			next&(name|scalar|objectOpen|arrayOpen) != 0 {
+			e.out = append(e.out, ',')
+			// For single-line output, add a random extra space after each
+			// comma to make output unstable.
+			if detrand.Bool() {
+				e.out = append(e.out, ' ')
+			}
+		}
+		return
+	}
+
+	switch {
+	case e.lastKind&(objectOpen|arrayOpen) != 0:
+		// If next type is NOT closing, add indent and newline.
+		if next&(objectClose|arrayClose) == 0 {
+			e.indents = append(e.indents, e.indent...)
+			e.out = append(e.out, '\n')
+			e.out = append(e.out, e.indents...)
+		}
+
+	case e.lastKind&(scalar|objectClose|arrayClose) != 0:
+		switch {
+		// If next type is either a value or name, add comma and newline.
+		case next&(name|scalar|objectOpen|arrayOpen) != 0:
+			e.out = append(e.out, ',', '\n')
+
+		// If next type is a closing object or array, adjust indentation.
+		case next&(objectClose|arrayClose) != 0:
+			e.indents = e.indents[:len(e.indents)-len(e.indent)]
+			e.out = append(e.out, '\n')
+		}
+		e.out = append(e.out, e.indents...)
+
+	case e.lastKind&name != 0:
+		e.out = append(e.out, ' ')
+		// For multi-line output, add a random extra space after key: to make
+		// output unstable.
+		if detrand.Bool() {
+			e.out = append(e.out, ' ')
+		}
+	}
+}