diff --git a/vendor/google.golang.org/protobuf/internal/impl/message_reflect_field.go b/vendor/google.golang.org/protobuf/internal/impl/message_reflect_field.go
new file mode 100644
index 0000000..343cf87
--- /dev/null
+++ b/vendor/google.golang.org/protobuf/internal/impl/message_reflect_field.go
@@ -0,0 +1,543 @@
+// 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 (
+	"fmt"
+	"math"
+	"reflect"
+	"sync"
+
+	"google.golang.org/protobuf/internal/flags"
+	pref "google.golang.org/protobuf/reflect/protoreflect"
+	preg "google.golang.org/protobuf/reflect/protoregistry"
+)
+
+type fieldInfo struct {
+	fieldDesc pref.FieldDescriptor
+
+	// These fields are used for protobuf reflection support.
+	has        func(pointer) bool
+	clear      func(pointer)
+	get        func(pointer) pref.Value
+	set        func(pointer, pref.Value)
+	mutable    func(pointer) pref.Value
+	newMessage func() pref.Message
+	newField   func() pref.Value
+}
+
+func fieldInfoForMissing(fd pref.FieldDescriptor) fieldInfo {
+	// This never occurs for generated message types.
+	// It implies that a hand-crafted type has missing Go fields
+	// for specific protobuf message fields.
+	return fieldInfo{
+		fieldDesc: fd,
+		has: func(p pointer) bool {
+			return false
+		},
+		clear: func(p pointer) {
+			panic("missing Go struct field for " + string(fd.FullName()))
+		},
+		get: func(p pointer) pref.Value {
+			return fd.Default()
+		},
+		set: func(p pointer, v pref.Value) {
+			panic("missing Go struct field for " + string(fd.FullName()))
+		},
+		mutable: func(p pointer) pref.Value {
+			panic("missing Go struct field for " + string(fd.FullName()))
+		},
+		newMessage: func() pref.Message {
+			panic("missing Go struct field for " + string(fd.FullName()))
+		},
+		newField: func() pref.Value {
+			if v := fd.Default(); v.IsValid() {
+				return v
+			}
+			panic("missing Go struct field for " + string(fd.FullName()))
+		},
+	}
+}
+
+func fieldInfoForOneof(fd pref.FieldDescriptor, fs reflect.StructField, x exporter, ot reflect.Type) fieldInfo {
+	ft := fs.Type
+	if ft.Kind() != reflect.Interface {
+		panic(fmt.Sprintf("field %v has invalid type: got %v, want interface kind", fd.FullName(), ft))
+	}
+	if ot.Kind() != reflect.Struct {
+		panic(fmt.Sprintf("field %v has invalid type: got %v, want struct kind", fd.FullName(), ot))
+	}
+	if !reflect.PtrTo(ot).Implements(ft) {
+		panic(fmt.Sprintf("field %v has invalid type: %v does not implement %v", fd.FullName(), ot, ft))
+	}
+	conv := NewConverter(ot.Field(0).Type, fd)
+	isMessage := fd.Message() != nil
+
+	// TODO: Implement unsafe fast path?
+	fieldOffset := offsetOf(fs, x)
+	return fieldInfo{
+		// NOTE: The logic below intentionally assumes that oneof fields are
+		// well-formatted. That is, the oneof interface never contains a
+		// typed nil pointer to one of the wrapper structs.
+
+		fieldDesc: fd,
+		has: func(p pointer) bool {
+			if p.IsNil() {
+				return false
+			}
+			rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem()
+			if rv.IsNil() || rv.Elem().Type().Elem() != ot || rv.Elem().IsNil() {
+				return false
+			}
+			return true
+		},
+		clear: func(p pointer) {
+			rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem()
+			if rv.IsNil() || rv.Elem().Type().Elem() != ot {
+				// NOTE: We intentionally don't check for rv.Elem().IsNil()
+				// so that (*OneofWrapperType)(nil) gets cleared to nil.
+				return
+			}
+			rv.Set(reflect.Zero(rv.Type()))
+		},
+		get: func(p pointer) pref.Value {
+			if p.IsNil() {
+				return conv.Zero()
+			}
+			rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem()
+			if rv.IsNil() || rv.Elem().Type().Elem() != ot || rv.Elem().IsNil() {
+				return conv.Zero()
+			}
+			rv = rv.Elem().Elem().Field(0)
+			return conv.PBValueOf(rv)
+		},
+		set: func(p pointer, v pref.Value) {
+			rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem()
+			if rv.IsNil() || rv.Elem().Type().Elem() != ot || rv.Elem().IsNil() {
+				rv.Set(reflect.New(ot))
+			}
+			rv = rv.Elem().Elem().Field(0)
+			rv.Set(conv.GoValueOf(v))
+		},
+		mutable: func(p pointer) pref.Value {
+			if !isMessage {
+				panic(fmt.Sprintf("field %v with invalid Mutable call on field with non-composite type", fd.FullName()))
+			}
+			rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem()
+			if rv.IsNil() || rv.Elem().Type().Elem() != ot || rv.Elem().IsNil() {
+				rv.Set(reflect.New(ot))
+			}
+			rv = rv.Elem().Elem().Field(0)
+			if rv.Kind() == reflect.Ptr && rv.IsNil() {
+				rv.Set(conv.GoValueOf(pref.ValueOfMessage(conv.New().Message())))
+			}
+			return conv.PBValueOf(rv)
+		},
+		newMessage: func() pref.Message {
+			return conv.New().Message()
+		},
+		newField: func() pref.Value {
+			return conv.New()
+		},
+	}
+}
+
+func fieldInfoForMap(fd pref.FieldDescriptor, fs reflect.StructField, x exporter) fieldInfo {
+	ft := fs.Type
+	if ft.Kind() != reflect.Map {
+		panic(fmt.Sprintf("field %v has invalid type: got %v, want map kind", fd.FullName(), ft))
+	}
+	conv := NewConverter(ft, fd)
+
+	// TODO: Implement unsafe fast path?
+	fieldOffset := offsetOf(fs, x)
+	return fieldInfo{
+		fieldDesc: fd,
+		has: func(p pointer) bool {
+			if p.IsNil() {
+				return false
+			}
+			rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem()
+			return rv.Len() > 0
+		},
+		clear: func(p pointer) {
+			rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem()
+			rv.Set(reflect.Zero(rv.Type()))
+		},
+		get: func(p pointer) pref.Value {
+			if p.IsNil() {
+				return conv.Zero()
+			}
+			rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem()
+			if rv.Len() == 0 {
+				return conv.Zero()
+			}
+			return conv.PBValueOf(rv)
+		},
+		set: func(p pointer, v pref.Value) {
+			rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem()
+			pv := conv.GoValueOf(v)
+			if pv.IsNil() {
+				panic(fmt.Sprintf("map field %v cannot be set with read-only value", fd.FullName()))
+			}
+			rv.Set(pv)
+		},
+		mutable: func(p pointer) pref.Value {
+			v := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem()
+			if v.IsNil() {
+				v.Set(reflect.MakeMap(fs.Type))
+			}
+			return conv.PBValueOf(v)
+		},
+		newField: func() pref.Value {
+			return conv.New()
+		},
+	}
+}
+
+func fieldInfoForList(fd pref.FieldDescriptor, fs reflect.StructField, x exporter) fieldInfo {
+	ft := fs.Type
+	if ft.Kind() != reflect.Slice {
+		panic(fmt.Sprintf("field %v has invalid type: got %v, want slice kind", fd.FullName(), ft))
+	}
+	conv := NewConverter(reflect.PtrTo(ft), fd)
+
+	// TODO: Implement unsafe fast path?
+	fieldOffset := offsetOf(fs, x)
+	return fieldInfo{
+		fieldDesc: fd,
+		has: func(p pointer) bool {
+			if p.IsNil() {
+				return false
+			}
+			rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem()
+			return rv.Len() > 0
+		},
+		clear: func(p pointer) {
+			rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem()
+			rv.Set(reflect.Zero(rv.Type()))
+		},
+		get: func(p pointer) pref.Value {
+			if p.IsNil() {
+				return conv.Zero()
+			}
+			rv := p.Apply(fieldOffset).AsValueOf(fs.Type)
+			if rv.Elem().Len() == 0 {
+				return conv.Zero()
+			}
+			return conv.PBValueOf(rv)
+		},
+		set: func(p pointer, v pref.Value) {
+			rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem()
+			pv := conv.GoValueOf(v)
+			if pv.IsNil() {
+				panic(fmt.Sprintf("list field %v cannot be set with read-only value", fd.FullName()))
+			}
+			rv.Set(pv.Elem())
+		},
+		mutable: func(p pointer) pref.Value {
+			v := p.Apply(fieldOffset).AsValueOf(fs.Type)
+			return conv.PBValueOf(v)
+		},
+		newField: func() pref.Value {
+			return conv.New()
+		},
+	}
+}
+
+var (
+	nilBytes   = reflect.ValueOf([]byte(nil))
+	emptyBytes = reflect.ValueOf([]byte{})
+)
+
+func fieldInfoForScalar(fd pref.FieldDescriptor, fs reflect.StructField, x exporter) fieldInfo {
+	ft := fs.Type
+	nullable := fd.HasPresence()
+	isBytes := ft.Kind() == reflect.Slice && ft.Elem().Kind() == reflect.Uint8
+	if nullable {
+		if ft.Kind() != reflect.Ptr && ft.Kind() != reflect.Slice {
+			// This never occurs for generated message types.
+			// Despite the protobuf type system specifying presence,
+			// the Go field type cannot represent it.
+			nullable = false
+		}
+		if ft.Kind() == reflect.Ptr {
+			ft = ft.Elem()
+		}
+	}
+	conv := NewConverter(ft, fd)
+
+	// TODO: Implement unsafe fast path?
+	fieldOffset := offsetOf(fs, x)
+	return fieldInfo{
+		fieldDesc: fd,
+		has: func(p pointer) bool {
+			if p.IsNil() {
+				return false
+			}
+			rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem()
+			if nullable {
+				return !rv.IsNil()
+			}
+			switch rv.Kind() {
+			case reflect.Bool:
+				return rv.Bool()
+			case reflect.Int32, reflect.Int64:
+				return rv.Int() != 0
+			case reflect.Uint32, reflect.Uint64:
+				return rv.Uint() != 0
+			case reflect.Float32, reflect.Float64:
+				return rv.Float() != 0 || math.Signbit(rv.Float())
+			case reflect.String, reflect.Slice:
+				return rv.Len() > 0
+			default:
+				panic(fmt.Sprintf("field %v has invalid type: %v", fd.FullName(), rv.Type())) // should never happen
+			}
+		},
+		clear: func(p pointer) {
+			rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem()
+			rv.Set(reflect.Zero(rv.Type()))
+		},
+		get: func(p pointer) pref.Value {
+			if p.IsNil() {
+				return conv.Zero()
+			}
+			rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem()
+			if nullable {
+				if rv.IsNil() {
+					return conv.Zero()
+				}
+				if rv.Kind() == reflect.Ptr {
+					rv = rv.Elem()
+				}
+			}
+			return conv.PBValueOf(rv)
+		},
+		set: func(p pointer, v pref.Value) {
+			rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem()
+			if nullable && rv.Kind() == reflect.Ptr {
+				if rv.IsNil() {
+					rv.Set(reflect.New(ft))
+				}
+				rv = rv.Elem()
+			}
+			rv.Set(conv.GoValueOf(v))
+			if isBytes && rv.Len() == 0 {
+				if nullable {
+					rv.Set(emptyBytes) // preserve presence
+				} else {
+					rv.Set(nilBytes) // do not preserve presence
+				}
+			}
+		},
+		newField: func() pref.Value {
+			return conv.New()
+		},
+	}
+}
+
+func fieldInfoForWeakMessage(fd pref.FieldDescriptor, weakOffset offset) fieldInfo {
+	if !flags.ProtoLegacy {
+		panic("no support for proto1 weak fields")
+	}
+
+	var once sync.Once
+	var messageType pref.MessageType
+	lazyInit := func() {
+		once.Do(func() {
+			messageName := fd.Message().FullName()
+			messageType, _ = preg.GlobalTypes.FindMessageByName(messageName)
+			if messageType == nil {
+				panic(fmt.Sprintf("weak message %v for field %v is not linked in", messageName, fd.FullName()))
+			}
+		})
+	}
+
+	num := fd.Number()
+	return fieldInfo{
+		fieldDesc: fd,
+		has: func(p pointer) bool {
+			if p.IsNil() {
+				return false
+			}
+			_, ok := p.Apply(weakOffset).WeakFields().get(num)
+			return ok
+		},
+		clear: func(p pointer) {
+			p.Apply(weakOffset).WeakFields().clear(num)
+		},
+		get: func(p pointer) pref.Value {
+			lazyInit()
+			if p.IsNil() {
+				return pref.ValueOfMessage(messageType.Zero())
+			}
+			m, ok := p.Apply(weakOffset).WeakFields().get(num)
+			if !ok {
+				return pref.ValueOfMessage(messageType.Zero())
+			}
+			return pref.ValueOfMessage(m.ProtoReflect())
+		},
+		set: func(p pointer, v pref.Value) {
+			lazyInit()
+			m := v.Message()
+			if m.Descriptor() != messageType.Descriptor() {
+				if got, want := m.Descriptor().FullName(), messageType.Descriptor().FullName(); got != want {
+					panic(fmt.Sprintf("field %v has mismatching message descriptor: got %v, want %v", fd.FullName(), got, want))
+				}
+				panic(fmt.Sprintf("field %v has mismatching message descriptor: %v", fd.FullName(), m.Descriptor().FullName()))
+			}
+			p.Apply(weakOffset).WeakFields().set(num, m.Interface())
+		},
+		mutable: func(p pointer) pref.Value {
+			lazyInit()
+			fs := p.Apply(weakOffset).WeakFields()
+			m, ok := fs.get(num)
+			if !ok {
+				m = messageType.New().Interface()
+				fs.set(num, m)
+			}
+			return pref.ValueOfMessage(m.ProtoReflect())
+		},
+		newMessage: func() pref.Message {
+			lazyInit()
+			return messageType.New()
+		},
+		newField: func() pref.Value {
+			lazyInit()
+			return pref.ValueOfMessage(messageType.New())
+		},
+	}
+}
+
+func fieldInfoForMessage(fd pref.FieldDescriptor, fs reflect.StructField, x exporter) fieldInfo {
+	ft := fs.Type
+	conv := NewConverter(ft, fd)
+
+	// TODO: Implement unsafe fast path?
+	fieldOffset := offsetOf(fs, x)
+	return fieldInfo{
+		fieldDesc: fd,
+		has: func(p pointer) bool {
+			if p.IsNil() {
+				return false
+			}
+			rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem()
+			if fs.Type.Kind() != reflect.Ptr {
+				return !isZero(rv)
+			}
+			return !rv.IsNil()
+		},
+		clear: func(p pointer) {
+			rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem()
+			rv.Set(reflect.Zero(rv.Type()))
+		},
+		get: func(p pointer) pref.Value {
+			if p.IsNil() {
+				return conv.Zero()
+			}
+			rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem()
+			return conv.PBValueOf(rv)
+		},
+		set: func(p pointer, v pref.Value) {
+			rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem()
+			rv.Set(conv.GoValueOf(v))
+			if fs.Type.Kind() == reflect.Ptr && rv.IsNil() {
+				panic(fmt.Sprintf("field %v has invalid nil pointer", fd.FullName()))
+			}
+		},
+		mutable: func(p pointer) pref.Value {
+			rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem()
+			if fs.Type.Kind() == reflect.Ptr && rv.IsNil() {
+				rv.Set(conv.GoValueOf(conv.New()))
+			}
+			return conv.PBValueOf(rv)
+		},
+		newMessage: func() pref.Message {
+			return conv.New().Message()
+		},
+		newField: func() pref.Value {
+			return conv.New()
+		},
+	}
+}
+
+type oneofInfo struct {
+	oneofDesc pref.OneofDescriptor
+	which     func(pointer) pref.FieldNumber
+}
+
+func makeOneofInfo(od pref.OneofDescriptor, si structInfo, x exporter) *oneofInfo {
+	oi := &oneofInfo{oneofDesc: od}
+	if od.IsSynthetic() {
+		fs := si.fieldsByNumber[od.Fields().Get(0).Number()]
+		fieldOffset := offsetOf(fs, x)
+		oi.which = func(p pointer) pref.FieldNumber {
+			if p.IsNil() {
+				return 0
+			}
+			rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem()
+			if rv.IsNil() { // valid on either *T or []byte
+				return 0
+			}
+			return od.Fields().Get(0).Number()
+		}
+	} else {
+		fs := si.oneofsByName[od.Name()]
+		fieldOffset := offsetOf(fs, x)
+		oi.which = func(p pointer) pref.FieldNumber {
+			if p.IsNil() {
+				return 0
+			}
+			rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem()
+			if rv.IsNil() {
+				return 0
+			}
+			rv = rv.Elem()
+			if rv.IsNil() {
+				return 0
+			}
+			return si.oneofWrappersByType[rv.Type().Elem()]
+		}
+	}
+	return oi
+}
+
+// isZero is identical to reflect.Value.IsZero.
+// TODO: Remove this when Go1.13 is the minimally supported Go version.
+func isZero(v reflect.Value) bool {
+	switch v.Kind() {
+	case reflect.Bool:
+		return !v.Bool()
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return v.Int() == 0
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		return v.Uint() == 0
+	case reflect.Float32, reflect.Float64:
+		return math.Float64bits(v.Float()) == 0
+	case reflect.Complex64, reflect.Complex128:
+		c := v.Complex()
+		return math.Float64bits(real(c)) == 0 && math.Float64bits(imag(c)) == 0
+	case reflect.Array:
+		for i := 0; i < v.Len(); i++ {
+			if !isZero(v.Index(i)) {
+				return false
+			}
+		}
+		return true
+	case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice, reflect.UnsafePointer:
+		return v.IsNil()
+	case reflect.String:
+		return v.Len() == 0
+	case reflect.Struct:
+		for i := 0; i < v.NumField(); i++ {
+			if !isZero(v.Field(i)) {
+				return false
+			}
+		}
+		return true
+	default:
+		panic(&reflect.ValueError{"reflect.Value.IsZero", v.Kind()})
+	}
+}