rebase: bump github.com/hashicorp/vault/api from 1.1.1 to 1.2.0

Bumps [github.com/hashicorp/vault/api](https://github.com/hashicorp/vault) from 1.1.1 to 1.2.0.
- [Release notes](https://github.com/hashicorp/vault/releases)
- [Changelog](https://github.com/hashicorp/vault/blob/main/CHANGELOG.md)
- [Commits](https://github.com/hashicorp/vault/compare/v1.1.1...v1.2.0)

---
updated-dependencies:
- dependency-name: github.com/hashicorp/vault/api
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

vendor/google.golang.org/grpc/health/client.go

@@ -0,0 +1,117 @@
+/*
+ *
+ * Copyright 2018 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 health
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"time"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/connectivity"
+	healthpb "google.golang.org/grpc/health/grpc_health_v1"
+	"google.golang.org/grpc/internal"
+	"google.golang.org/grpc/internal/backoff"
+	"google.golang.org/grpc/status"
+)
+
+var (
+	backoffStrategy = backoff.DefaultExponential
+	backoffFunc     = func(ctx context.Context, retries int) bool {
+		d := backoffStrategy.Backoff(retries)
+		timer := time.NewTimer(d)
+		select {
+		case <-timer.C:
+			return true
+		case <-ctx.Done():
+			timer.Stop()
+			return false
+		}
+	}
+)
+
+func init() {
+	internal.HealthCheckFunc = clientHealthCheck
+}
+
+const healthCheckMethod = "/grpc.health.v1.Health/Watch"
+
+// This function implements the protocol defined at:
+// https://github.com/grpc/grpc/blob/master/doc/health-checking.md
+func clientHealthCheck(ctx context.Context, newStream func(string) (interface{}, error), setConnectivityState func(connectivity.State, error), service string) error {
+	tryCnt := 0
+
+retryConnection:
+	for {
+		// Backs off if the connection has failed in some way without receiving a message in the previous retry.
+		if tryCnt > 0 && !backoffFunc(ctx, tryCnt-1) {
+			return nil
+		}
+		tryCnt++
+
+		if ctx.Err() != nil {
+			return nil
+		}
+		setConnectivityState(connectivity.Connecting, nil)
+		rawS, err := newStream(healthCheckMethod)
+		if err != nil {
+			continue retryConnection
+		}
+
+		s, ok := rawS.(grpc.ClientStream)
+		// Ideally, this should never happen. But if it happens, the server is marked as healthy for LBing purposes.
+		if !ok {
+			setConnectivityState(connectivity.Ready, nil)
+			return fmt.Errorf("newStream returned %v (type %T); want grpc.ClientStream", rawS, rawS)
+		}
+
+		if err = s.SendMsg(&healthpb.HealthCheckRequest{Service: service}); err != nil && err != io.EOF {
+			// Stream should have been closed, so we can safely continue to create a new stream.
+			continue retryConnection
+		}
+		s.CloseSend()
+
+		resp := new(healthpb.HealthCheckResponse)
+		for {
+			err = s.RecvMsg(resp)
+
+			// Reports healthy for the LBing purposes if health check is not implemented in the server.
+			if status.Code(err) == codes.Unimplemented {
+				setConnectivityState(connectivity.Ready, nil)
+				return err
+			}
+
+			// Reports unhealthy if server's Watch method gives an error other than UNIMPLEMENTED.
+			if err != nil {
+				setConnectivityState(connectivity.TransientFailure, fmt.Errorf("connection active but received health check RPC error: %v", err))
+				continue retryConnection
+			}
+
+			// As a message has been received, removes the need for backoff for the next retry by resetting the try count.
+			tryCnt = 0
+			if resp.Status == healthpb.HealthCheckResponse_SERVING {
+				setConnectivityState(connectivity.Ready, nil)
+			} else {
+				setConnectivityState(connectivity.TransientFailure, fmt.Errorf("connection active but health check failed. status=%s", resp.Status))
+			}
+		}
+	}
+}