Update google.golang.org/grpc from v1.27.1 to v1.38.0

v1.38.0 is used by Kubernetes since
https://github.com/kubernetes/kubernetes/pull/100488.

Signed-off-by: Kazuyoshi Kato <katokazu@amazon.com>

vendor/google.golang.org/grpc/internal/xds_handshake_cluster.go

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2021 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 internal
+
+import (
+	"google.golang.org/grpc/attributes"
+	"google.golang.org/grpc/resolver"
+)
+
+// handshakeClusterNameKey is the type used as the key to store cluster name in
+// the Attributes field of resolver.Address.
+type handshakeClusterNameKey struct{}
+
+// SetXDSHandshakeClusterName returns a copy of addr in which the Attributes field
+// is updated with the cluster name.
+func SetXDSHandshakeClusterName(addr resolver.Address, clusterName string) resolver.Address {
+	addr.Attributes = addr.Attributes.WithValues(handshakeClusterNameKey{}, clusterName)
+	return addr
+}
+
+// GetXDSHandshakeClusterName returns cluster name stored in attr.
+func GetXDSHandshakeClusterName(attr *attributes.Attributes) (string, bool) {
+	v := attr.Value(handshakeClusterNameKey{})
+	name, ok := v.(string)
+	return name, ok
+}