diff --git a/vendor/google.golang.org/protobuf/internal/impl/legacy_message.go b/vendor/google.golang.org/protobuf/internal/impl/legacy_message.go
new file mode 100644
index 0000000..06c68e1
--- /dev/null
+++ b/vendor/google.golang.org/protobuf/internal/impl/legacy_message.go
@@ -0,0 +1,502 @@
+// 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"
+	"reflect"
+	"strings"
+	"sync"
+
+	"google.golang.org/protobuf/internal/descopts"
+	ptag "google.golang.org/protobuf/internal/encoding/tag"
+	"google.golang.org/protobuf/internal/errors"
+	"google.golang.org/protobuf/internal/filedesc"
+	"google.golang.org/protobuf/internal/strs"
+	"google.golang.org/protobuf/reflect/protoreflect"
+	pref "google.golang.org/protobuf/reflect/protoreflect"
+	"google.golang.org/protobuf/runtime/protoiface"
+	piface "google.golang.org/protobuf/runtime/protoiface"
+)
+
+// legacyWrapMessage wraps v as a protoreflect.Message,
+// where v must be a *struct kind and not implement the v2 API already.
+func legacyWrapMessage(v reflect.Value) pref.Message {
+	typ := v.Type()
+	if typ.Kind() != reflect.Ptr || typ.Elem().Kind() != reflect.Struct {
+		return aberrantMessage{v: v}
+	}
+	mt := legacyLoadMessageInfo(typ, "")
+	return mt.MessageOf(v.Interface())
+}
+
+var legacyMessageTypeCache sync.Map // map[reflect.Type]*MessageInfo
+
+// legacyLoadMessageInfo dynamically loads a *MessageInfo for t,
+// where t must be a *struct kind and not implement the v2 API already.
+// The provided name is used if it cannot be determined from the message.
+func legacyLoadMessageInfo(t reflect.Type, name pref.FullName) *MessageInfo {
+	// Fast-path: check if a MessageInfo is cached for this concrete type.
+	if mt, ok := legacyMessageTypeCache.Load(t); ok {
+		return mt.(*MessageInfo)
+	}
+
+	// Slow-path: derive message descriptor and initialize MessageInfo.
+	mi := &MessageInfo{
+		Desc:          legacyLoadMessageDesc(t, name),
+		GoReflectType: t,
+	}
+
+	v := reflect.Zero(t).Interface()
+	if _, ok := v.(legacyMarshaler); ok {
+		mi.methods.Marshal = legacyMarshal
+
+		// We have no way to tell whether the type's Marshal method
+		// supports deterministic serialization or not, but this
+		// preserves the v1 implementation's behavior of always
+		// calling Marshal methods when present.
+		mi.methods.Flags |= piface.SupportMarshalDeterministic
+	}
+	if _, ok := v.(legacyUnmarshaler); ok {
+		mi.methods.Unmarshal = legacyUnmarshal
+	}
+	if _, ok := v.(legacyMerger); ok {
+		mi.methods.Merge = legacyMerge
+	}
+
+	if mi, ok := legacyMessageTypeCache.LoadOrStore(t, mi); ok {
+		return mi.(*MessageInfo)
+	}
+	return mi
+}
+
+var legacyMessageDescCache sync.Map // map[reflect.Type]protoreflect.MessageDescriptor
+
+// LegacyLoadMessageDesc returns an MessageDescriptor derived from the Go type,
+// which must be a *struct kind and not implement the v2 API already.
+//
+// This is exported for testing purposes.
+func LegacyLoadMessageDesc(t reflect.Type) pref.MessageDescriptor {
+	return legacyLoadMessageDesc(t, "")
+}
+func legacyLoadMessageDesc(t reflect.Type, name pref.FullName) pref.MessageDescriptor {
+	// Fast-path: check if a MessageDescriptor is cached for this concrete type.
+	if mi, ok := legacyMessageDescCache.Load(t); ok {
+		return mi.(pref.MessageDescriptor)
+	}
+
+	// Slow-path: initialize MessageDescriptor from the raw descriptor.
+	mv := reflect.Zero(t).Interface()
+	if _, ok := mv.(pref.ProtoMessage); ok {
+		panic(fmt.Sprintf("%v already implements proto.Message", t))
+	}
+	mdV1, ok := mv.(messageV1)
+	if !ok {
+		return aberrantLoadMessageDesc(t, name)
+	}
+
+	// If this is a dynamic message type where there isn't a 1-1 mapping between
+	// Go and protobuf types, calling the Descriptor method on the zero value of
+	// the message type isn't likely to work. If it panics, swallow the panic and
+	// continue as if the Descriptor method wasn't present.
+	b, idxs := func() ([]byte, []int) {
+		defer func() {
+			recover()
+		}()
+		return mdV1.Descriptor()
+	}()
+	if b == nil {
+		return aberrantLoadMessageDesc(t, name)
+	}
+
+	// If the Go type has no fields, then this might be a proto3 empty message
+	// from before the size cache was added. If there are any fields, check to
+	// see that at least one of them looks like something we generated.
+	if nfield := t.Elem().NumField(); nfield > 0 {
+		hasProtoField := false
+		for i := 0; i < nfield; i++ {
+			f := t.Elem().Field(i)
+			if f.Tag.Get("protobuf") != "" || f.Tag.Get("protobuf_oneof") != "" || strings.HasPrefix(f.Name, "XXX_") {
+				hasProtoField = true
+				break
+			}
+		}
+		if !hasProtoField {
+			return aberrantLoadMessageDesc(t, name)
+		}
+	}
+
+	md := legacyLoadFileDesc(b).Messages().Get(idxs[0])
+	for _, i := range idxs[1:] {
+		md = md.Messages().Get(i)
+	}
+	if name != "" && md.FullName() != name {
+		panic(fmt.Sprintf("mismatching message name: got %v, want %v", md.FullName(), name))
+	}
+	if md, ok := legacyMessageDescCache.LoadOrStore(t, md); ok {
+		return md.(protoreflect.MessageDescriptor)
+	}
+	return md
+}
+
+var (
+	aberrantMessageDescLock  sync.Mutex
+	aberrantMessageDescCache map[reflect.Type]protoreflect.MessageDescriptor
+)
+
+// aberrantLoadMessageDesc returns an MessageDescriptor derived from the Go type,
+// which must not implement protoreflect.ProtoMessage or messageV1.
+//
+// This is a best-effort derivation of the message descriptor using the protobuf
+// tags on the struct fields.
+func aberrantLoadMessageDesc(t reflect.Type, name pref.FullName) pref.MessageDescriptor {
+	aberrantMessageDescLock.Lock()
+	defer aberrantMessageDescLock.Unlock()
+	if aberrantMessageDescCache == nil {
+		aberrantMessageDescCache = make(map[reflect.Type]protoreflect.MessageDescriptor)
+	}
+	return aberrantLoadMessageDescReentrant(t, name)
+}
+func aberrantLoadMessageDescReentrant(t reflect.Type, name pref.FullName) pref.MessageDescriptor {
+	// Fast-path: check if an MessageDescriptor is cached for this concrete type.
+	if md, ok := aberrantMessageDescCache[t]; ok {
+		return md
+	}
+
+	// Slow-path: construct a descriptor from the Go struct type (best-effort).
+	// Cache the MessageDescriptor early on so that we can resolve internal
+	// cyclic references.
+	md := &filedesc.Message{L2: new(filedesc.MessageL2)}
+	md.L0.FullName = aberrantDeriveMessageName(t, name)
+	md.L0.ParentFile = filedesc.SurrogateProto2
+	aberrantMessageDescCache[t] = md
+
+	if t.Kind() != reflect.Ptr || t.Elem().Kind() != reflect.Struct {
+		return md
+	}
+
+	// Try to determine if the message is using proto3 by checking scalars.
+	for i := 0; i < t.Elem().NumField(); i++ {
+		f := t.Elem().Field(i)
+		if tag := f.Tag.Get("protobuf"); tag != "" {
+			switch f.Type.Kind() {
+			case reflect.Bool, reflect.Int32, reflect.Int64, reflect.Uint32, reflect.Uint64, reflect.Float32, reflect.Float64, reflect.String:
+				md.L0.ParentFile = filedesc.SurrogateProto3
+			}
+			for _, s := range strings.Split(tag, ",") {
+				if s == "proto3" {
+					md.L0.ParentFile = filedesc.SurrogateProto3
+				}
+			}
+		}
+	}
+
+	// Obtain a list of oneof wrapper types.
+	var oneofWrappers []reflect.Type
+	for _, method := range []string{"XXX_OneofFuncs", "XXX_OneofWrappers"} {
+		if fn, ok := t.MethodByName(method); ok {
+			for _, v := range fn.Func.Call([]reflect.Value{reflect.Zero(fn.Type.In(0))}) {
+				if vs, ok := v.Interface().([]interface{}); ok {
+					for _, v := range vs {
+						oneofWrappers = append(oneofWrappers, reflect.TypeOf(v))
+					}
+				}
+			}
+		}
+	}
+
+	// Obtain a list of the extension ranges.
+	if fn, ok := t.MethodByName("ExtensionRangeArray"); ok {
+		vs := fn.Func.Call([]reflect.Value{reflect.Zero(fn.Type.In(0))})[0]
+		for i := 0; i < vs.Len(); i++ {
+			v := vs.Index(i)
+			md.L2.ExtensionRanges.List = append(md.L2.ExtensionRanges.List, [2]pref.FieldNumber{
+				pref.FieldNumber(v.FieldByName("Start").Int()),
+				pref.FieldNumber(v.FieldByName("End").Int() + 1),
+			})
+			md.L2.ExtensionRangeOptions = append(md.L2.ExtensionRangeOptions, nil)
+		}
+	}
+
+	// Derive the message fields by inspecting the struct fields.
+	for i := 0; i < t.Elem().NumField(); i++ {
+		f := t.Elem().Field(i)
+		if tag := f.Tag.Get("protobuf"); tag != "" {
+			tagKey := f.Tag.Get("protobuf_key")
+			tagVal := f.Tag.Get("protobuf_val")
+			aberrantAppendField(md, f.Type, tag, tagKey, tagVal)
+		}
+		if tag := f.Tag.Get("protobuf_oneof"); tag != "" {
+			n := len(md.L2.Oneofs.List)
+			md.L2.Oneofs.List = append(md.L2.Oneofs.List, filedesc.Oneof{})
+			od := &md.L2.Oneofs.List[n]
+			od.L0.FullName = md.FullName().Append(pref.Name(tag))
+			od.L0.ParentFile = md.L0.ParentFile
+			od.L0.Parent = md
+			od.L0.Index = n
+
+			for _, t := range oneofWrappers {
+				if t.Implements(f.Type) {
+					f := t.Elem().Field(0)
+					if tag := f.Tag.Get("protobuf"); tag != "" {
+						aberrantAppendField(md, f.Type, tag, "", "")
+						fd := &md.L2.Fields.List[len(md.L2.Fields.List)-1]
+						fd.L1.ContainingOneof = od
+						od.L1.Fields.List = append(od.L1.Fields.List, fd)
+					}
+				}
+			}
+		}
+	}
+
+	return md
+}
+
+func aberrantDeriveMessageName(t reflect.Type, name pref.FullName) pref.FullName {
+	if name.IsValid() {
+		return name
+	}
+	func() {
+		defer func() { recover() }() // swallow possible nil panics
+		if m, ok := reflect.Zero(t).Interface().(interface{ XXX_MessageName() string }); ok {
+			name = pref.FullName(m.XXX_MessageName())
+		}
+	}()
+	if name.IsValid() {
+		return name
+	}
+	if t.Kind() == reflect.Ptr {
+		t = t.Elem()
+	}
+	return AberrantDeriveFullName(t)
+}
+
+func aberrantAppendField(md *filedesc.Message, goType reflect.Type, tag, tagKey, tagVal string) {
+	t := goType
+	isOptional := t.Kind() == reflect.Ptr && t.Elem().Kind() != reflect.Struct
+	isRepeated := t.Kind() == reflect.Slice && t.Elem().Kind() != reflect.Uint8
+	if isOptional || isRepeated {
+		t = t.Elem()
+	}
+	fd := ptag.Unmarshal(tag, t, placeholderEnumValues{}).(*filedesc.Field)
+
+	// Append field descriptor to the message.
+	n := len(md.L2.Fields.List)
+	md.L2.Fields.List = append(md.L2.Fields.List, *fd)
+	fd = &md.L2.Fields.List[n]
+	fd.L0.FullName = md.FullName().Append(fd.Name())
+	fd.L0.ParentFile = md.L0.ParentFile
+	fd.L0.Parent = md
+	fd.L0.Index = n
+
+	if fd.L1.IsWeak || fd.L1.HasPacked {
+		fd.L1.Options = func() pref.ProtoMessage {
+			opts := descopts.Field.ProtoReflect().New()
+			if fd.L1.IsWeak {
+				opts.Set(opts.Descriptor().Fields().ByName("weak"), protoreflect.ValueOfBool(true))
+			}
+			if fd.L1.HasPacked {
+				opts.Set(opts.Descriptor().Fields().ByName("packed"), protoreflect.ValueOfBool(fd.L1.IsPacked))
+			}
+			return opts.Interface()
+		}
+	}
+
+	// Populate Enum and Message.
+	if fd.Enum() == nil && fd.Kind() == pref.EnumKind {
+		switch v := reflect.Zero(t).Interface().(type) {
+		case pref.Enum:
+			fd.L1.Enum = v.Descriptor()
+		default:
+			fd.L1.Enum = LegacyLoadEnumDesc(t)
+		}
+	}
+	if fd.Message() == nil && (fd.Kind() == pref.MessageKind || fd.Kind() == pref.GroupKind) {
+		switch v := reflect.Zero(t).Interface().(type) {
+		case pref.ProtoMessage:
+			fd.L1.Message = v.ProtoReflect().Descriptor()
+		case messageV1:
+			fd.L1.Message = LegacyLoadMessageDesc(t)
+		default:
+			if t.Kind() == reflect.Map {
+				n := len(md.L1.Messages.List)
+				md.L1.Messages.List = append(md.L1.Messages.List, filedesc.Message{L2: new(filedesc.MessageL2)})
+				md2 := &md.L1.Messages.List[n]
+				md2.L0.FullName = md.FullName().Append(pref.Name(strs.MapEntryName(string(fd.Name()))))
+				md2.L0.ParentFile = md.L0.ParentFile
+				md2.L0.Parent = md
+				md2.L0.Index = n
+
+				md2.L1.IsMapEntry = true
+				md2.L2.Options = func() pref.ProtoMessage {
+					opts := descopts.Message.ProtoReflect().New()
+					opts.Set(opts.Descriptor().Fields().ByName("map_entry"), protoreflect.ValueOfBool(true))
+					return opts.Interface()
+				}
+
+				aberrantAppendField(md2, t.Key(), tagKey, "", "")
+				aberrantAppendField(md2, t.Elem(), tagVal, "", "")
+
+				fd.L1.Message = md2
+				break
+			}
+			fd.L1.Message = aberrantLoadMessageDescReentrant(t, "")
+		}
+	}
+}
+
+type placeholderEnumValues struct {
+	protoreflect.EnumValueDescriptors
+}
+
+func (placeholderEnumValues) ByNumber(n pref.EnumNumber) pref.EnumValueDescriptor {
+	return filedesc.PlaceholderEnumValue(pref.FullName(fmt.Sprintf("UNKNOWN_%d", n)))
+}
+
+// legacyMarshaler is the proto.Marshaler interface superseded by protoiface.Methoder.
+type legacyMarshaler interface {
+	Marshal() ([]byte, error)
+}
+
+// legacyUnmarshaler is the proto.Unmarshaler interface superseded by protoiface.Methoder.
+type legacyUnmarshaler interface {
+	Unmarshal([]byte) error
+}
+
+// legacyMerger is the proto.Merger interface superseded by protoiface.Methoder.
+type legacyMerger interface {
+	Merge(protoiface.MessageV1)
+}
+
+var legacyProtoMethods = &piface.Methods{
+	Marshal:   legacyMarshal,
+	Unmarshal: legacyUnmarshal,
+	Merge:     legacyMerge,
+
+	// We have no way to tell whether the type's Marshal method
+	// supports deterministic serialization or not, but this
+	// preserves the v1 implementation's behavior of always
+	// calling Marshal methods when present.
+	Flags: piface.SupportMarshalDeterministic,
+}
+
+func legacyMarshal(in piface.MarshalInput) (piface.MarshalOutput, error) {
+	v := in.Message.(unwrapper).protoUnwrap()
+	marshaler, ok := v.(legacyMarshaler)
+	if !ok {
+		return piface.MarshalOutput{}, errors.New("%T does not implement Marshal", v)
+	}
+	out, err := marshaler.Marshal()
+	if in.Buf != nil {
+		out = append(in.Buf, out...)
+	}
+	return piface.MarshalOutput{
+		Buf: out,
+	}, err
+}
+
+func legacyUnmarshal(in piface.UnmarshalInput) (piface.UnmarshalOutput, error) {
+	v := in.Message.(unwrapper).protoUnwrap()
+	unmarshaler, ok := v.(legacyUnmarshaler)
+	if !ok {
+		return piface.UnmarshalOutput{}, errors.New("%T does not implement Marshal", v)
+	}
+	return piface.UnmarshalOutput{}, unmarshaler.Unmarshal(in.Buf)
+}
+
+func legacyMerge(in piface.MergeInput) piface.MergeOutput {
+	dstv := in.Destination.(unwrapper).protoUnwrap()
+	merger, ok := dstv.(legacyMerger)
+	if !ok {
+		return piface.MergeOutput{}
+	}
+	merger.Merge(Export{}.ProtoMessageV1Of(in.Source))
+	return piface.MergeOutput{Flags: piface.MergeComplete}
+}
+
+// aberrantMessageType implements MessageType for all types other than pointer-to-struct.
+type aberrantMessageType struct {
+	t reflect.Type
+}
+
+func (mt aberrantMessageType) New() pref.Message {
+	return aberrantMessage{reflect.Zero(mt.t)}
+}
+func (mt aberrantMessageType) Zero() pref.Message {
+	return aberrantMessage{reflect.Zero(mt.t)}
+}
+func (mt aberrantMessageType) GoType() reflect.Type {
+	return mt.t
+}
+func (mt aberrantMessageType) Descriptor() pref.MessageDescriptor {
+	return LegacyLoadMessageDesc(mt.t)
+}
+
+// aberrantMessage implements Message for all types other than pointer-to-struct.
+//
+// When the underlying type implements legacyMarshaler or legacyUnmarshaler,
+// the aberrant Message can be marshaled or unmarshaled. Otherwise, there is
+// not much that can be done with values of this type.
+type aberrantMessage struct {
+	v reflect.Value
+}
+
+func (m aberrantMessage) ProtoReflect() pref.Message {
+	return m
+}
+
+func (m aberrantMessage) Descriptor() pref.MessageDescriptor {
+	return LegacyLoadMessageDesc(m.v.Type())
+}
+func (m aberrantMessage) Type() pref.MessageType {
+	return aberrantMessageType{m.v.Type()}
+}
+func (m aberrantMessage) New() pref.Message {
+	return aberrantMessage{reflect.Zero(m.v.Type())}
+}
+func (m aberrantMessage) Interface() pref.ProtoMessage {
+	return m
+}
+func (m aberrantMessage) Range(f func(pref.FieldDescriptor, pref.Value) bool) {
+}
+func (m aberrantMessage) Has(pref.FieldDescriptor) bool {
+	panic("invalid field descriptor")
+}
+func (m aberrantMessage) Clear(pref.FieldDescriptor) {
+	panic("invalid field descriptor")
+}
+func (m aberrantMessage) Get(pref.FieldDescriptor) pref.Value {
+	panic("invalid field descriptor")
+}
+func (m aberrantMessage) Set(pref.FieldDescriptor, pref.Value) {
+	panic("invalid field descriptor")
+}
+func (m aberrantMessage) Mutable(pref.FieldDescriptor) pref.Value {
+	panic("invalid field descriptor")
+}
+func (m aberrantMessage) NewField(pref.FieldDescriptor) pref.Value {
+	panic("invalid field descriptor")
+}
+func (m aberrantMessage) WhichOneof(pref.OneofDescriptor) pref.FieldDescriptor {
+	panic("invalid oneof descriptor")
+}
+func (m aberrantMessage) GetUnknown() pref.RawFields {
+	return nil
+}
+func (m aberrantMessage) SetUnknown(pref.RawFields) {
+	// SetUnknown discards its input on messages which don't support unknown field storage.
+}
+func (m aberrantMessage) IsValid() bool {
+	// An invalid message is a read-only, empty message. Since we don't know anything
+	// about the alleged contents of this message, we can't say with confidence that
+	// it is invalid in this sense. Therefore, report it as valid.
+	return true
+}
+func (m aberrantMessage) ProtoMethods() *piface.Methods {
+	return legacyProtoMethods
+}
+func (m aberrantMessage) protoUnwrap() interface{} {
+	return m.v.Interface()
+}