diff --git a/vendor/google.golang.org/grpc/credentials/credentials.go b/vendor/google.golang.org/grpc/credentials/credentials.go
index a671107..96ff187 100644
--- a/vendor/google.golang.org/grpc/credentials/credentials.go
+++ b/vendor/google.golang.org/grpc/credentials/credentials.go
@@ -178,8 +178,18 @@
 //
 // This API is experimental.
 type Bundle interface {
+	// TransportCredentials returns the transport credentials from the Bundle.
+	//
+	// Implementations must return non-nil transport credentials. If transport
+	// security is not needed by the Bundle, implementations may choose to
+	// return insecure.NewCredentials().
 	TransportCredentials() TransportCredentials
+
+	// PerRPCCredentials returns the per-RPC credentials from the Bundle.
+	//
+	// May be nil if per-RPC credentials are not needed.
 	PerRPCCredentials() PerRPCCredentials
+
 	// NewWithMode should make a copy of Bundle, and switch mode. Modifying the
 	// existing Bundle may cause races.
 	//
diff --git a/vendor/google.golang.org/grpc/credentials/insecure/insecure.go b/vendor/google.golang.org/grpc/credentials/insecure/insecure.go
new file mode 100644
index 0000000..4fbed12
--- /dev/null
+++ b/vendor/google.golang.org/grpc/credentials/insecure/insecure.go
@@ -0,0 +1,72 @@
+/*
+ *
+ * Copyright 2020 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Package insecure provides an implementation of the
+// credentials.TransportCredentials interface which disables transport security.
+package insecure
+
+import (
+	"context"
+	"net"
+
+	"google.golang.org/grpc/credentials"
+)
+
+// NewCredentials returns a credentials which disables transport security.
+//
+// Note that using this credentials with per-RPC credentials which require
+// transport security is incompatible and will cause grpc.Dial() to fail.
+func NewCredentials() credentials.TransportCredentials {
+	return insecureTC{}
+}
+
+// insecureTC implements the insecure transport credentials. The handshake
+// methods simply return the passed in net.Conn and set the security level to
+// NoSecurity.
+type insecureTC struct{}
+
+func (insecureTC) ClientHandshake(ctx context.Context, _ string, conn net.Conn) (net.Conn, credentials.AuthInfo, error) {
+	return conn, info{credentials.CommonAuthInfo{SecurityLevel: credentials.NoSecurity}}, nil
+}
+
+func (insecureTC) ServerHandshake(conn net.Conn) (net.Conn, credentials.AuthInfo, error) {
+	return conn, info{credentials.CommonAuthInfo{SecurityLevel: credentials.NoSecurity}}, nil
+}
+
+func (insecureTC) Info() credentials.ProtocolInfo {
+	return credentials.ProtocolInfo{SecurityProtocol: "insecure"}
+}
+
+func (insecureTC) Clone() credentials.TransportCredentials {
+	return insecureTC{}
+}
+
+func (insecureTC) OverrideServerName(string) error {
+	return nil
+}
+
+// info contains the auth information for an insecure connection.
+// It implements the AuthInfo interface.
+type info struct {
+	credentials.CommonAuthInfo
+}
+
+// AuthType returns the type of info as a string.
+func (info) AuthType() string {
+	return "insecure"
+}