diff --git a/vendor/google.golang.org/protobuf/proto/extension.go b/vendor/google.golang.org/protobuf/proto/extension.go
new file mode 100644
index 0000000..5f293cd
--- /dev/null
+++ b/vendor/google.golang.org/protobuf/proto/extension.go
@@ -0,0 +1,92 @@
+// 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.
+
+package proto
+
+import (
+	"google.golang.org/protobuf/reflect/protoreflect"
+)
+
+// HasExtension reports whether an extension field is populated.
+// It returns false if m is invalid or if xt does not extend m.
+func HasExtension(m Message, xt protoreflect.ExtensionType) bool {
+	// Treat nil message interface as an empty message; no populated fields.
+	if m == nil {
+		return false
+	}
+
+	// As a special-case, we reports invalid or mismatching descriptors
+	// as always not being populated (since they aren't).
+	if xt == nil || m.ProtoReflect().Descriptor() != xt.TypeDescriptor().ContainingMessage() {
+		return false
+	}
+
+	return m.ProtoReflect().Has(xt.TypeDescriptor())
+}
+
+// ClearExtension clears an extension field such that subsequent
+// HasExtension calls return false.
+// It panics if m is invalid or if xt does not extend m.
+func ClearExtension(m Message, xt protoreflect.ExtensionType) {
+	m.ProtoReflect().Clear(xt.TypeDescriptor())
+}
+
+// GetExtension retrieves the value for an extension field.
+// If the field is unpopulated, it returns the default value for
+// scalars and an immutable, empty value for lists or messages.
+// It panics if xt does not extend m.
+func GetExtension(m Message, xt protoreflect.ExtensionType) interface{} {
+	// Treat nil message interface as an empty message; return the default.
+	if m == nil {
+		return xt.InterfaceOf(xt.Zero())
+	}
+
+	return xt.InterfaceOf(m.ProtoReflect().Get(xt.TypeDescriptor()))
+}
+
+// SetExtension stores the value of an extension field.
+// It panics if m is invalid, xt does not extend m, or if type of v
+// is invalid for the specified extension field.
+func SetExtension(m Message, xt protoreflect.ExtensionType, v interface{}) {
+	xd := xt.TypeDescriptor()
+	pv := xt.ValueOf(v)
+
+	// Specially treat an invalid list, map, or message as clear.
+	isValid := true
+	switch {
+	case xd.IsList():
+		isValid = pv.List().IsValid()
+	case xd.IsMap():
+		isValid = pv.Map().IsValid()
+	case xd.Message() != nil:
+		isValid = pv.Message().IsValid()
+	}
+	if !isValid {
+		m.ProtoReflect().Clear(xd)
+		return
+	}
+
+	m.ProtoReflect().Set(xd, pv)
+}
+
+// RangeExtensions iterates over every populated extension field in m in an
+// undefined order, calling f for each extension type and value encountered.
+// It returns immediately if f returns false.
+// While iterating, mutating operations may only be performed
+// on the current extension field.
+func RangeExtensions(m Message, f func(protoreflect.ExtensionType, interface{}) bool) {
+	// Treat nil message interface as an empty message; nothing to range over.
+	if m == nil {
+		return
+	}
+
+	m.ProtoReflect().Range(func(fd protoreflect.FieldDescriptor, v protoreflect.Value) bool {
+		if fd.IsExtension() {
+			xt := fd.(protoreflect.ExtensionTypeDescriptor).Type()
+			vi := xt.InterfaceOf(v)
+			return f(xt, vi)
+		}
+		return true
+	})
+}