diff --git a/vendor/google.golang.org/grpc/vet.sh b/vendor/google.golang.org/grpc/vet.sh
new file mode 100755
index 0000000..7209aa5
--- /dev/null
+++ b/vendor/google.golang.org/grpc/vet.sh
@@ -0,0 +1,123 @@
+#!/bin/bash
+
+if [[ `uname -a` = *"Darwin"* ]]; then
+  echo "It seems you are running on Mac. This script does not work on Mac. See https://github.com/grpc/grpc-go/issues/2047"
+  exit 1
+fi
+
+set -ex  # Exit on error; debugging enabled.
+set -o pipefail  # Fail a pipe if any sub-command fails.
+
+die() {
+  echo "$@" >&2
+  exit 1
+}
+
+fail_on_output() {
+  tee /dev/stderr | (! read)
+}
+
+# Check to make sure it's safe to modify the user's git repo.
+git status --porcelain | fail_on_output
+
+# Undo any edits made by this script.
+cleanup() {
+  git reset --hard HEAD
+}
+trap cleanup EXIT
+
+PATH="${GOPATH}/bin:${GOROOT}/bin:${PATH}"
+
+if [[ "$1" = "-install" ]]; then
+  # Check for module support
+  if go help mod >& /dev/null; then
+    go install \
+      golang.org/x/lint/golint \
+      golang.org/x/tools/cmd/goimports \
+      honnef.co/go/tools/cmd/staticcheck \
+      github.com/client9/misspell/cmd/misspell \
+      github.com/golang/protobuf/protoc-gen-go
+  else
+    # Ye olde `go get` incantation.
+    # Note: this gets the latest version of all tools (vs. the pinned versions
+    # with Go modules).
+    go get -u \
+      golang.org/x/lint/golint \
+      golang.org/x/tools/cmd/goimports \
+      honnef.co/go/tools/cmd/staticcheck \
+      github.com/client9/misspell/cmd/misspell \
+      github.com/golang/protobuf/protoc-gen-go
+  fi
+  if [[ -z "${VET_SKIP_PROTO}" ]]; then
+    if [[ "${TRAVIS}" = "true" ]]; then
+      PROTOBUF_VERSION=3.3.0
+      PROTOC_FILENAME=protoc-${PROTOBUF_VERSION}-linux-x86_64.zip
+      pushd /home/travis
+      wget https://github.com/google/protobuf/releases/download/v${PROTOBUF_VERSION}/${PROTOC_FILENAME}
+      unzip ${PROTOC_FILENAME}
+      bin/protoc --version
+      popd
+    elif ! which protoc > /dev/null; then
+      die "Please install protoc into your path"
+    fi
+  fi
+  exit 0
+elif [[ "$#" -ne 0 ]]; then
+  die "Unknown argument(s): $*"
+fi
+
+# - Ensure all source files contain a copyright message.
+git ls-files "*.go" | xargs grep -L "\(Copyright [0-9]\{4,\} gRPC authors\)\|DO NOT EDIT" 2>&1 | fail_on_output
+
+# - Make sure all tests in grpc and grpc/test use leakcheck via Teardown.
+(! grep 'func Test[^(]' *_test.go)
+(! grep 'func Test[^(]' test/*.go)
+
+# - Do not import math/rand for real library code.  Use internal/grpcrand for
+#   thread safety.
+git ls-files "*.go" | xargs grep -l '"math/rand"' 2>&1 | (! grep -v '^examples\|^stress\|grpcrand')
+
+# - Ensure all ptypes proto packages are renamed when importing.
+git ls-files "*.go" | (! xargs grep "\(import \|^\s*\)\"github.com/golang/protobuf/ptypes/")
+
+# - Check imports that are illegal in appengine (until Go 1.11).
+# TODO: Remove when we drop Go 1.10 support
+go list -f {{.Dir}} ./... | xargs go run test/go_vet/vet.go
+
+# - gofmt, goimports, golint (with exceptions for generated code), go vet.
+gofmt -s -d -l . 2>&1 | fail_on_output
+goimports -l . 2>&1 | fail_on_output
+golint ./... 2>&1 | (! grep -vE "(_mock|\.pb)\.go:")
+go tool vet -all .
+
+# - Check that generated proto files are up to date.
+if [[ -z "${VET_SKIP_PROTO}" ]]; then
+  PATH="/home/travis/bin:${PATH}" make proto && \
+    git status --porcelain 2>&1 | fail_on_output || \
+    (git status; git --no-pager diff; exit 1)
+fi
+
+# - Check that our module is tidy.
+if go help mod >& /dev/null; then
+  go mod tidy && \
+    git status --porcelain 2>&1 | fail_on_output || \
+    (git status; git --no-pager diff; exit 1)
+fi
+
+# - Collection of static analysis checks
+# TODO(menghanl): fix errors in transport_test.
+staticcheck -go 1.9 -checks 'inherit,-ST1015' -ignore '
+google.golang.org/grpc/balancer.go:SA1019
+google.golang.org/grpc/balancer_test.go:SA1019
+google.golang.org/grpc/clientconn_test.go:SA1019
+google.golang.org/grpc/balancer/roundrobin/roundrobin_test.go:SA1019
+google.golang.org/grpc/benchmark/benchmain/main.go:SA1019
+google.golang.org/grpc/benchmark/worker/benchmark_client.go:SA1019
+google.golang.org/grpc/internal/transport/handler_server.go:SA1019
+google.golang.org/grpc/internal/transport/handler_server_test.go:SA1019
+google.golang.org/grpc/stats/stats_test.go:SA1019
+google.golang.org/grpc/test/channelz_test.go:SA1019
+google.golang.org/grpc/test/end2end_test.go:SA1019
+google.golang.org/grpc/test/healthcheck_test.go:SA1019
+' ./...
+misspell -error .