diff --git a/vendor/github.com/golang/protobuf/proto/discard.go b/vendor/github.com/golang/protobuf/proto/discard.go
index 2187e87..dea2617 100644
--- a/vendor/github.com/golang/protobuf/proto/discard.go
+++ b/vendor/github.com/golang/protobuf/proto/discard.go
@@ -1,13 +1,48 @@
-// 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.
+// Go support for Protocol Buffers - Google's data interchange format
+//
+// Copyright 2017 The Go Authors.  All rights reserved.
+// https://github.com/golang/protobuf
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 package proto
 
 import (
-	"google.golang.org/protobuf/reflect/protoreflect"
+	"fmt"
+	"reflect"
+	"strings"
+	"sync"
+	"sync/atomic"
 )
 
+type generatedDiscarder interface {
+	XXX_DiscardUnknown()
+}
+
 // DiscardUnknown recursively discards all unknown fields from this message
 // and all embedded messages.
 //
@@ -16,43 +51,300 @@
 // marshal to be able to produce a message that continues to have those
 // unrecognized fields. To avoid this, DiscardUnknown is used to
 // explicitly clear the unknown fields after unmarshaling.
+//
+// For proto2 messages, the unknown fields of message extensions are only
+// discarded from messages that have been accessed via GetExtension.
 func DiscardUnknown(m Message) {
-	if m != nil {
-		discardUnknown(MessageReflect(m))
+	if m, ok := m.(generatedDiscarder); ok {
+		m.XXX_DiscardUnknown()
+		return
+	}
+	// TODO: Dynamically populate a InternalMessageInfo for legacy messages,
+	// but the master branch has no implementation for InternalMessageInfo,
+	// so it would be more work to replicate that approach.
+	discardLegacy(m)
+}
+
+// DiscardUnknown recursively discards all unknown fields.
+func (a *InternalMessageInfo) DiscardUnknown(m Message) {
+	di := atomicLoadDiscardInfo(&a.discard)
+	if di == nil {
+		di = getDiscardInfo(reflect.TypeOf(m).Elem())
+		atomicStoreDiscardInfo(&a.discard, di)
+	}
+	di.discard(toPointer(&m))
+}
+
+type discardInfo struct {
+	typ reflect.Type
+
+	initialized int32 // 0: only typ is valid, 1: everything is valid
+	lock        sync.Mutex
+
+	fields       []discardFieldInfo
+	unrecognized field
+}
+
+type discardFieldInfo struct {
+	field   field // Offset of field, guaranteed to be valid
+	discard func(src pointer)
+}
+
+var (
+	discardInfoMap  = map[reflect.Type]*discardInfo{}
+	discardInfoLock sync.Mutex
+)
+
+func getDiscardInfo(t reflect.Type) *discardInfo {
+	discardInfoLock.Lock()
+	defer discardInfoLock.Unlock()
+	di := discardInfoMap[t]
+	if di == nil {
+		di = &discardInfo{typ: t}
+		discardInfoMap[t] = di
+	}
+	return di
+}
+
+func (di *discardInfo) discard(src pointer) {
+	if src.isNil() {
+		return // Nothing to do.
+	}
+
+	if atomic.LoadInt32(&di.initialized) == 0 {
+		di.computeDiscardInfo()
+	}
+
+	for _, fi := range di.fields {
+		sfp := src.offset(fi.field)
+		fi.discard(sfp)
+	}
+
+	// For proto2 messages, only discard unknown fields in message extensions
+	// that have been accessed via GetExtension.
+	if em, err := extendable(src.asPointerTo(di.typ).Interface()); err == nil {
+		// Ignore lock since DiscardUnknown is not concurrency safe.
+		emm, _ := em.extensionsRead()
+		for _, mx := range emm {
+			if m, ok := mx.value.(Message); ok {
+				DiscardUnknown(m)
+			}
+		}
+	}
+
+	if di.unrecognized.IsValid() {
+		*src.offset(di.unrecognized).toBytes() = nil
 	}
 }
 
-func discardUnknown(m protoreflect.Message) {
-	m.Range(func(fd protoreflect.FieldDescriptor, val protoreflect.Value) bool {
-		switch {
-		// Handle singular message.
-		case fd.Cardinality() != protoreflect.Repeated:
-			if fd.Message() != nil {
-				discardUnknown(m.Get(fd).Message())
-			}
-		// Handle list of messages.
-		case fd.IsList():
-			if fd.Message() != nil {
-				ls := m.Get(fd).List()
-				for i := 0; i < ls.Len(); i++ {
-					discardUnknown(ls.Get(i).Message())
+func (di *discardInfo) computeDiscardInfo() {
+	di.lock.Lock()
+	defer di.lock.Unlock()
+	if di.initialized != 0 {
+		return
+	}
+	t := di.typ
+	n := t.NumField()
+
+	for i := 0; i < n; i++ {
+		f := t.Field(i)
+		if strings.HasPrefix(f.Name, "XXX_") {
+			continue
+		}
+
+		dfi := discardFieldInfo{field: toField(&f)}
+		tf := f.Type
+
+		// Unwrap tf to get its most basic type.
+		var isPointer, isSlice bool
+		if tf.Kind() == reflect.Slice && tf.Elem().Kind() != reflect.Uint8 {
+			isSlice = true
+			tf = tf.Elem()
+		}
+		if tf.Kind() == reflect.Ptr {
+			isPointer = true
+			tf = tf.Elem()
+		}
+		if isPointer && isSlice && tf.Kind() != reflect.Struct {
+			panic(fmt.Sprintf("%v.%s cannot be a slice of pointers to primitive types", t, f.Name))
+		}
+
+		switch tf.Kind() {
+		case reflect.Struct:
+			switch {
+			case !isPointer:
+				panic(fmt.Sprintf("%v.%s cannot be a direct struct value", t, f.Name))
+			case isSlice: // E.g., []*pb.T
+				di := getDiscardInfo(tf)
+				dfi.discard = func(src pointer) {
+					sps := src.getPointerSlice()
+					for _, sp := range sps {
+						if !sp.isNil() {
+							di.discard(sp)
+						}
+					}
+				}
+			default: // E.g., *pb.T
+				di := getDiscardInfo(tf)
+				dfi.discard = func(src pointer) {
+					sp := src.getPointer()
+					if !sp.isNil() {
+						di.discard(sp)
+					}
 				}
 			}
-		// Handle map of messages.
-		case fd.IsMap():
-			if fd.MapValue().Message() != nil {
-				ms := m.Get(fd).Map()
-				ms.Range(func(_ protoreflect.MapKey, v protoreflect.Value) bool {
-					discardUnknown(v.Message())
-					return true
-				})
+		case reflect.Map:
+			switch {
+			case isPointer || isSlice:
+				panic(fmt.Sprintf("%v.%s cannot be a pointer to a map or a slice of map values", t, f.Name))
+			default: // E.g., map[K]V
+				if tf.Elem().Kind() == reflect.Ptr { // Proto struct (e.g., *T)
+					dfi.discard = func(src pointer) {
+						sm := src.asPointerTo(tf).Elem()
+						if sm.Len() == 0 {
+							return
+						}
+						for _, key := range sm.MapKeys() {
+							val := sm.MapIndex(key)
+							DiscardUnknown(val.Interface().(Message))
+						}
+					}
+				} else {
+					dfi.discard = func(pointer) {} // Noop
+				}
+			}
+		case reflect.Interface:
+			// Must be oneof field.
+			switch {
+			case isPointer || isSlice:
+				panic(fmt.Sprintf("%v.%s cannot be a pointer to a interface or a slice of interface values", t, f.Name))
+			default: // E.g., interface{}
+				// TODO: Make this faster?
+				dfi.discard = func(src pointer) {
+					su := src.asPointerTo(tf).Elem()
+					if !su.IsNil() {
+						sv := su.Elem().Elem().Field(0)
+						if sv.Kind() == reflect.Ptr && sv.IsNil() {
+							return
+						}
+						switch sv.Type().Kind() {
+						case reflect.Ptr: // Proto struct (e.g., *T)
+							DiscardUnknown(sv.Interface().(Message))
+						}
+					}
+				}
+			}
+		default:
+			continue
+		}
+		di.fields = append(di.fields, dfi)
+	}
+
+	di.unrecognized = invalidField
+	if f, ok := t.FieldByName("XXX_unrecognized"); ok {
+		if f.Type != reflect.TypeOf([]byte{}) {
+			panic("expected XXX_unrecognized to be of type []byte")
+		}
+		di.unrecognized = toField(&f)
+	}
+
+	atomic.StoreInt32(&di.initialized, 1)
+}
+
+func discardLegacy(m Message) {
+	v := reflect.ValueOf(m)
+	if v.Kind() != reflect.Ptr || v.IsNil() {
+		return
+	}
+	v = v.Elem()
+	if v.Kind() != reflect.Struct {
+		return
+	}
+	t := v.Type()
+
+	for i := 0; i < v.NumField(); i++ {
+		f := t.Field(i)
+		if strings.HasPrefix(f.Name, "XXX_") {
+			continue
+		}
+		vf := v.Field(i)
+		tf := f.Type
+
+		// Unwrap tf to get its most basic type.
+		var isPointer, isSlice bool
+		if tf.Kind() == reflect.Slice && tf.Elem().Kind() != reflect.Uint8 {
+			isSlice = true
+			tf = tf.Elem()
+		}
+		if tf.Kind() == reflect.Ptr {
+			isPointer = true
+			tf = tf.Elem()
+		}
+		if isPointer && isSlice && tf.Kind() != reflect.Struct {
+			panic(fmt.Sprintf("%T.%s cannot be a slice of pointers to primitive types", m, f.Name))
+		}
+
+		switch tf.Kind() {
+		case reflect.Struct:
+			switch {
+			case !isPointer:
+				panic(fmt.Sprintf("%T.%s cannot be a direct struct value", m, f.Name))
+			case isSlice: // E.g., []*pb.T
+				for j := 0; j < vf.Len(); j++ {
+					discardLegacy(vf.Index(j).Interface().(Message))
+				}
+			default: // E.g., *pb.T
+				discardLegacy(vf.Interface().(Message))
+			}
+		case reflect.Map:
+			switch {
+			case isPointer || isSlice:
+				panic(fmt.Sprintf("%T.%s cannot be a pointer to a map or a slice of map values", m, f.Name))
+			default: // E.g., map[K]V
+				tv := vf.Type().Elem()
+				if tv.Kind() == reflect.Ptr && tv.Implements(protoMessageType) { // Proto struct (e.g., *T)
+					for _, key := range vf.MapKeys() {
+						val := vf.MapIndex(key)
+						discardLegacy(val.Interface().(Message))
+					}
+				}
+			}
+		case reflect.Interface:
+			// Must be oneof field.
+			switch {
+			case isPointer || isSlice:
+				panic(fmt.Sprintf("%T.%s cannot be a pointer to a interface or a slice of interface values", m, f.Name))
+			default: // E.g., test_proto.isCommunique_Union interface
+				if !vf.IsNil() && f.Tag.Get("protobuf_oneof") != "" {
+					vf = vf.Elem() // E.g., *test_proto.Communique_Msg
+					if !vf.IsNil() {
+						vf = vf.Elem()   // E.g., test_proto.Communique_Msg
+						vf = vf.Field(0) // E.g., Proto struct (e.g., *T) or primitive value
+						if vf.Kind() == reflect.Ptr {
+							discardLegacy(vf.Interface().(Message))
+						}
+					}
+				}
 			}
 		}
-		return true
-	})
+	}
 
-	// Discard unknown fields.
-	if len(m.GetUnknown()) > 0 {
-		m.SetUnknown(nil)
+	if vf := v.FieldByName("XXX_unrecognized"); vf.IsValid() {
+		if vf.Type() != reflect.TypeOf([]byte{}) {
+			panic("expected XXX_unrecognized to be of type []byte")
+		}
+		vf.Set(reflect.ValueOf([]byte(nil)))
+	}
+
+	// For proto2 messages, only discard unknown fields in message extensions
+	// that have been accessed via GetExtension.
+	if em, err := extendable(m); err == nil {
+		// Ignore lock since discardLegacy is not concurrency safe.
+		emm, _ := em.extensionsRead()
+		for _, mx := range emm {
+			if m, ok := mx.value.(Message); ok {
+				discardLegacy(m)
+			}
+		}
 	}
 }