improve metadata handling

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

.gitea/ISSUE_TEMPLATE/question.md

@@ -1,14 +0,0 @@
----
-name: Question
-about: Ask a question about go-micro
-title: ''
-labels: ''
-assignees: ''
-
----
-
-Before asking, please check if your question has already been answered: 
-
-1. Check the documentation - https://micro.mu/docs/
-2. Check the examples and plugins - https://github.com/micro/examples & https://github.com/micro/go-plugins
-3. Search existing issues

.github/ISSUE_TEMPLATE/bug_report.md

@@ -1,6 +1,6 @@
 ---
 name: Bug report
-about: For reporting bugs in go-micro
+about: For reporting bugs in micro
 title: "[BUG]"
 labels: ''
 assignees: ''
@@ -16,9 +16,3 @@ assignees: ''
 **How to reproduce the bug:**
 
 If possible, please include a minimal code snippet here.
-
-**Environment:**
-Go Version: please paste `go version` output here
-```
-please paste `go env` output here
-```

.github/ISSUE_TEMPLATE/feature-request---enhancement.md

@@ -1,6 +1,6 @@
 ---
 name: Feature request / Enhancement
-about: If you have a need not served by go-micro
+about: If you have a need not served by micro
 title: "[FEATURE]"
 labels: ''
 assignees: ''
@@ -14,4 +14,4 @@ A clear and concise description of what the problem is. Ex. I'm always frustrate
 A clear and concise description of what you want to happen.
 
 **Additional context**
-Add any other context or screenshots about the feature request here.
+Add any other context or screenshots about the feature request here.

.github/ISSUE_TEMPLATE/question.md

@@ -0,0 +1,8 @@
+---
+name: Question
+about: Ask a question about micro
+title: ''
+labels: ''
+assignees: ''
+
+---

.github/autoapprove.yml

@@ -0,0 +1,28 @@
+name: "autoapprove"
+
+on:
+  pull_request_target:
+    types: [assigned, opened, synchronize, reopened]
+  workflow_run:
+    workflows: ["prbuild"]
+    types:
+      - completed
+
+permissions:
+  pull-requests: write
+  contents: write
+
+jobs:
+  autoapprove:
+    runs-on: ubuntu-latest
+    steps:
+      - name: approve
+        run: [ "curl -o tea https://dl.gitea.com/tea/main/tea-main-linux-amd64",
+               "chmod +x ./tea",
+               "./tea login add --name unistack --token ${{ secrets.GITHUB_TOKEN }} --url https://git.unistack.org",
+               "./tea pr --repo ${{ github.event.repository.name }}"
+        ]
+        if: github.actor == 'vtolstov'
+        id: approve
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/job_coverage.yml

@@ -0,0 +1,53 @@
+name: coverage
+
+on:
+  push:
+    branches: [ main, v3, v4 ]
+    paths-ignore:
+      - '.github/**'
+      - '.gitea/**'
+  pull_request:
+    branches: [ main, v3, v4 ]
+
+jobs:
+
+  build:
+    if: github.server_url != 'https://github.com'
+    runs-on: ubuntu-latest
+    steps:
+    - name: checkout code
+      uses: actions/checkout@v4
+      with:
+        filter: 'blob:none'
+
+    - name: setup go
+      uses: actions/setup-go@v5
+      with:
+        cache-dependency-path: "**/*.sum"
+        go-version: 'stable'
+
+    - name: test coverage
+      run: |
+        go test -v -cover ./... -covermode=count -coverprofile coverage.out -coverpkg ./...
+        go tool cover -func coverage.out -o coverage.out
+
+    - name: coverage badge
+      uses: tj-actions/coverage-badge-go@v2
+      with:
+        green: 80
+        filename: coverage.out
+
+    - uses: stefanzweifel/git-auto-commit-action@v4
+      name: autocommit
+      with:
+        commit_message: Apply Code Coverage Badge
+        skip_fetch: false
+        skip_checkout: false
+        file_pattern: ./README.md
+
+    - name: push
+      if: steps.auto-commit-action.outputs.changes_detected == 'true'
+      uses: ad-m/github-push-action@master
+      with:
+        github_token: ${{ github.token }}
+        branch: ${{ github.ref }}

.github/workflows/job_lint.yml

@@ -3,10 +3,10 @@ name: lint
 on:
   pull_request:
     types: [opened, reopened, synchronize]
-    branches:
+    branches: [ master, v3, v4 ]
-    - master
+    paths-ignore:
-    - v3
+      - '.github/**'
-    - v4
+      - '.gitea/**'
 
 jobs:
   lint:
@@ -20,10 +20,10 @@ jobs:
       uses: actions/setup-go@v5
       with:
         cache-dependency-path: "**/*.sum"
-        go-version: 'stable' 
+        go-version: 'stable'
     - name: setup deps
       run: go get -v ./...
     - name: run lint
-      uses: https://github.com/golangci/golangci-lint-action@v6
+      uses: golangci/golangci-lint-action@v6
       with:
         version: 'latest'

.github/workflows/job_sync.yml

@@ -0,0 +1,94 @@
+name: sync
+
+on:
+  schedule:
+    - cron: '*/5 * * * *'
+  # Allows you to run this workflow manually from the Actions tab
+  workflow_dispatch:
+
+jobs:
+  sync:
+    if: github.server_url != 'https://github.com'
+    runs-on: ubuntu-latest
+    steps:
+    - name: init
+      run: |
+        git config --global user.email "vtolstov <vtolstov@users.noreply.github.com>"
+        git config --global user.name "github-actions[bot]"
+        echo "machine git.unistack.org login vtolstov password ${{ secrets.TOKEN_GITEA }}" >> /root/.netrc
+        echo "machine github.com login vtolstov password ${{ secrets.TOKEN_GITHUB }}" >> /root/.netrc
+
+    - name: check master
+      id: check_master
+      run: |
+        src_hash=$(git ls-remote https://github.com/${GITHUB_REPOSITORY} refs/heads/master | cut -f1)
+        dst_hash=$(git ls-remote ${GITHUB_SERVER_URL}/${GITHUB_REPOSITORY} refs/heads/master | cut -f1)
+        echo "src_hash=$src_hash"
+        echo "dst_hash=$dst_hash"
+        if [ "$src_hash" != "$dst_hash" ]; then
+          echo "sync_needed=true" >> $GITHUB_OUTPUT
+        else
+          echo "sync_needed=false" >> $GITHUB_OUTPUT
+        fi
+
+    - name: sync master
+      if: steps.check_master.outputs.sync_needed == 'true'
+      run: |
+        git clone --filter=blob:none --filter=tree:0 --branch master --single-branch ${GITHUB_SERVER_URL}/${GITHUB_REPOSITORY} repo
+        cd repo
+        git remote add --no-tags --fetch --track master upstream https://github.com/${GITHUB_REPOSITORY}
+        git pull --rebase upstream master
+        git push upstream master --progress
+        git push origin master --progress
+        cd ../
+        rm -rf repo
+
+    - name: check v3
+      id: check_v3
+      run: |
+        src_hash=$(git ls-remote https://github.com/${GITHUB_REPOSITORY} refs/heads/v3 | cut -f1)
+        dst_hash=$(git ls-remote ${GITHUB_SERVER_URL}/${GITHUB_REPOSITORY} refs/heads/v3 | cut -f1)
+        echo "src_hash=$src_hash"
+        echo "dst_hash=$dst_hash"
+        if [ "$src_hash" != "$dst_hash" ]; then
+          echo "sync_needed=true" >> $GITHUB_OUTPUT
+        else
+          echo "sync_needed=false" >> $GITHUB_OUTPUT
+        fi
+
+    - name: sync v3
+      if: steps.check_v3.outputs.sync_needed == 'true'
+      run: |
+        git clone --filter=blob:none --filter=tree:0 --branch v3 --single-branch ${GITHUB_SERVER_URL}/${GITHUB_REPOSITORY} repo
+        cd repo
+        git remote add --no-tags --fetch --track v3 upstream https://github.com/${GITHUB_REPOSITORY}
+        git pull --rebase upstream v3
+        git push upstream v3 --progress
+        git push origin v3 --progress
+        cd ../
+        rm -rf repo
+
+    - name: check v4
+      id: check_v4
+      run: |
+        src_hash=$(git ls-remote https://github.com/${GITHUB_REPOSITORY} refs/heads/v4 | cut -f1)
+        dst_hash=$(git ls-remote ${GITHUB_SERVER_URL}/${GITHUB_REPOSITORY} refs/heads/v4 | cut -f1)
+        echo "src_hash=$src_hash"
+        echo "dst_hash=$dst_hash"
+        if [ "$src_hash" != "$dst_hash" ]; then
+          echo "sync_needed=true" >> $GITHUB_OUTPUT
+        else
+          echo "sync_needed=false" >> $GITHUB_OUTPUT
+        fi
+
+    - name: sync v4
+      if: steps.check_v4.outputs.sync_needed == 'true'
+      run: |
+        git clone --filter=blob:none --filter=tree:0 --branch v4 --single-branch ${GITHUB_SERVER_URL}/${GITHUB_REPOSITORY} repo
+        cd repo
+        git remote add --no-tags --fetch --track v4 upstream https://github.com/${GITHUB_REPOSITORY}
+        git pull --rebase upstream v4
+        git push upstream v4 --progress
+        git push origin v4 --progress
+        cd ../
+        rm -rf repo

.github/workflows/job_test.yml

@@ -3,15 +3,12 @@ name: test
 on:
   pull_request:
     types: [opened, reopened, synchronize]
-    branches:
+    branches: [ master, v3, v4 ]
-    - master
-    - v3
-    - v4
   push:
-    branches:
+    branches: [ master, v3, v4 ]
-    - master
+    paths-ignore:
-    - v3
+      - '.github/**'
-    - v4
+      - '.gitea/**'
 
 jobs:
   test:

.github/workflows/job_tests.yml

@@ -3,15 +3,12 @@ name: test
 on:
   pull_request:
     types: [opened, reopened, synchronize]
-    branches:
+    branches: [ master, v3, v4 ]
-    - master
-    - v3
-    - v4
   push:
-    branches:
+    branches: [ master, v3, v4 ]
-    - master
+    paths-ignore:
-    - v3
+      - '.github/**'
-    - v4
+      - '.gitea/**'
 
 jobs:
   test:
@@ -35,19 +32,19 @@ jobs:
         go-version: 'stable'
     - name: setup go work
       env:
-        GOWORK: /workspace/${{ github.repository_owner }}/go.work
+        GOWORK: ${{ github.workspace }}/go.work
       run: |
         go work init
         go work use .
-        go work use micro-tests        
+        go work use micro-tests
     - name: setup deps
       env:
-        GOWORK: /workspace/${{ github.repository_owner }}/go.work
+        GOWORK: ${{ github.workspace }}/go.work
       run: go get -v ./...
     - name: run tests
       env:
         INTEGRATION_TESTS: yes
-        GOWORK: /workspace/${{ github.repository_owner }}/go.work
+        GOWORK: ${{ github.workspace }}/go.work
       run: |
         cd micro-tests
-        go test -mod readonly -v ./... || true        
+        go test -mod readonly -v ./... || true

.golangci.yml

@@ -1,5 +1,5 @@
 run:
   concurrency: 8
-  deadline: 5m
+  timeout: 5m
   issues-exit-code: 1
   tests: true

README.md

@@ -0,0 +1,4 @@
+# GRPC Client
+![Coverage](https://img.shields.io/badge/Coverage-2.3%25-red)
+
+This plugin is a grpc client for micro.

go.mod

@@ -5,8 +5,8 @@ go 1.23.0
 toolchain go1.23.3
 
 require (
-	go.unistack.org/micro/v4 v4.1.2
+	go.unistack.org/micro/v4 v4.1.7
-	google.golang.org/grpc v1.70.0
+	google.golang.org/grpc v1.72.0
 )
 
 require (
@@ -15,10 +15,10 @@ require (
 	github.com/matoous/go-nanoid v1.5.1 // indirect
 	github.com/spf13/cast v1.7.1 // indirect
 	go.unistack.org/micro-proto/v4 v4.1.0 // indirect
-	golang.org/x/net v0.35.0 // indirect
+	golang.org/x/net v0.39.0 // indirect
-	golang.org/x/sys v0.30.0 // indirect
+	golang.org/x/sys v0.32.0 // indirect
-	golang.org/x/text v0.22.0 // indirect
+	golang.org/x/text v0.24.0 // indirect
-	google.golang.org/genproto/googleapis/rpc v0.0.0-20250224174004-546df14abb99 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20250425173222-7b384671a197 // indirect
-	google.golang.org/protobuf v1.36.5 // indirect
+	google.golang.org/protobuf v1.36.6 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -24,32 +24,34 @@ github.com/rogpeppe/go-internal v1.13.1 h1:KvO1DLK/DRN07sQ1LQKScxyZJuNnedQ5/wKSR
 github.com/rogpeppe/go-internal v1.13.1/go.mod h1:uMEvuHeurkdAXX61udpOXGD/AzZDWNMNyH2VO9fmH0o=
 github.com/spf13/cast v1.7.1 h1:cuNEagBQEHWN1FnbGEjCXL2szYEXqfJPbP2HNUaca9Y=
 github.com/spf13/cast v1.7.1/go.mod h1:ancEpBxwJDODSW/UG4rDrAqiKolqNNh2DX3mk86cAdo=
-go.opentelemetry.io/otel v1.32.0 h1:WnBN+Xjcteh0zdk01SVqV55d/m62NJLJdIyb4y/WO5U=
+go.opentelemetry.io/auto/sdk v1.1.0 h1:cH53jehLUN6UFLY71z+NDOiNJqDdPRaXzTel0sJySYA=
-go.opentelemetry.io/otel v1.32.0/go.mod h1:00DCVSB0RQcnzlwyTfqtxSm+DRr9hpYrHjNGiBHVQIg=
+go.opentelemetry.io/auto/sdk v1.1.0/go.mod h1:3wSPjt5PWp2RhlCcmmOial7AvC4DQqZb7a7wCow3W8A=
-go.opentelemetry.io/otel/metric v1.32.0 h1:xV2umtmNcThh2/a/aCP+h64Xx5wsj8qqnkYZktzNa0M=
+go.opentelemetry.io/otel v1.34.0 h1:zRLXxLCgL1WyKsPVrgbSdMN4c0FMkDAskSTQP+0hdUY=
-go.opentelemetry.io/otel/metric v1.32.0/go.mod h1:jH7CIbbK6SH2V2wE16W05BHCtIDzauciCRLoc/SyMv8=
+go.opentelemetry.io/otel v1.34.0/go.mod h1:OWFPOQ+h4G8xpyjgqo4SxJYdDQ/qmRH+wivy7zzx9oI=
-go.opentelemetry.io/otel/sdk v1.32.0 h1:RNxepc9vK59A8XsgZQouW8ue8Gkb4jpWtJm9ge5lEG4=
+go.opentelemetry.io/otel/metric v1.34.0 h1:+eTR3U0MyfWjRDhmFMxe2SsW64QrZ84AOhvqS7Y+PoQ=
-go.opentelemetry.io/otel/sdk v1.32.0/go.mod h1:LqgegDBjKMmb2GC6/PrTnteJG39I8/vJCAP9LlJXEjU=
+go.opentelemetry.io/otel/metric v1.34.0/go.mod h1:CEDrp0fy2D0MvkXE+dPV7cMi8tWZwX3dmaIhwPOaqHE=
-go.opentelemetry.io/otel/sdk/metric v1.32.0 h1:rZvFnvmvawYb0alrYkjraqJq0Z4ZUJAiyYCU9snn1CU=
+go.opentelemetry.io/otel/sdk v1.34.0 h1:95zS4k/2GOy069d321O8jWgYsW3MzVV+KuSPKp7Wr1A=
-go.opentelemetry.io/otel/sdk/metric v1.32.0/go.mod h1:PWeZlq0zt9YkYAp3gjKZ0eicRYvOh1Gd+X99x6GHpCQ=
+go.opentelemetry.io/otel/sdk v1.34.0/go.mod h1:0e/pNiaMAqaykJGKbi+tSjWfNNHMTxoC9qANsCzbyxU=
-go.opentelemetry.io/otel/trace v1.32.0 h1:WIC9mYrXf8TmY/EXuULKc8hR17vE+Hjv2cssQDe03fM=
+go.opentelemetry.io/otel/sdk/metric v1.34.0 h1:5CeK9ujjbFVL5c1PhLuStg1wxA7vQv7ce1EK0Gyvahk=
-go.opentelemetry.io/otel/trace v1.32.0/go.mod h1:+i4rkvCraA+tG6AzwloGaCtkx53Fa+L+V8e9a7YvhT8=
+go.opentelemetry.io/otel/sdk/metric v1.34.0/go.mod h1:jQ/r8Ze28zRKoNRdkjCZxfs6YvBTG1+YIqyFVFYec5w=
+go.opentelemetry.io/otel/trace v1.34.0 h1:+ouXS2V8Rd4hp4580a8q23bg0azF2nI8cqLYnC8mh/k=
+go.opentelemetry.io/otel/trace v1.34.0/go.mod h1:Svm7lSjQD7kG7KJ/MUHPVXSDGz2OX4h0M2jHBhmSfRE=
 go.unistack.org/micro-proto/v4 v4.1.0 h1:qPwL2n/oqh9RE3RTTDgt28XK3QzV597VugQPaw9lKUk=
 go.unistack.org/micro-proto/v4 v4.1.0/go.mod h1:ArmK7o+uFvxSY3dbJhKBBX4Pm1rhWdLEFf3LxBrMtec=
-go.unistack.org/micro/v4 v4.1.2 h1:9SOlPYyPNNFpg1A7BsvhDyQm3gysLH1AhWbDCp1hyoY=
+go.unistack.org/micro/v4 v4.1.7 h1:4/dSEMTqxYoHimn/8wKDohfTXi2zDy6eWXYBCnBaZdc=
-go.unistack.org/micro/v4 v4.1.2/go.mod h1:lr3oYED8Ay1vjK68QqRw30QOtdk/ffpZqMFDasOUhKw=
+go.unistack.org/micro/v4 v4.1.7/go.mod h1:lr3oYED8Ay1vjK68QqRw30QOtdk/ffpZqMFDasOUhKw=
-golang.org/x/net v0.35.0 h1:T5GQRQb2y08kTAByq9L4/bz8cipCdA8FbRTXewonqY8=
+golang.org/x/net v0.39.0 h1:ZCu7HMWDxpXpaiKdhzIfaltL9Lp31x/3fCP11bc6/fY=
-golang.org/x/net v0.35.0/go.mod h1:EglIi67kWsHKlRzzVMUD93VMSWGFOMSZgxFjparz1Qk=
+golang.org/x/net v0.39.0/go.mod h1:X7NRbYVEA+ewNkCNyJ513WmMdQ3BineSwVtN2zD/d+E=
-golang.org/x/sys v0.30.0 h1:QjkSwP/36a20jFYWkSue1YwXzLmsV5Gfq7Eiy72C1uc=
+golang.org/x/sys v0.32.0 h1:s77OFDvIQeibCmezSnk/q6iAfkdiQaJi4VzroCFrN20=
-golang.org/x/sys v0.30.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/sys v0.32.0/go.mod h1:BJP2sWEmIv4KK5OTEluFJCKSidICx8ciO85XgH3Ak8k=
-golang.org/x/text v0.22.0 h1:bofq7m3/HAFvbF51jz3Q9wLg3jkvSPuiZu/pD1XwgtM=
+golang.org/x/text v0.24.0 h1:dd5Bzh4yt5KYA8f9CJHCP4FB4D51c2c6JvN37xJJkJ0=
-golang.org/x/text v0.22.0/go.mod h1:YRoo4H8PVmsu+E3Ou7cqLVH8oXWIHVoX0jqUWALQhfY=
+golang.org/x/text v0.24.0/go.mod h1:L8rBsPeo2pSS+xqN0d5u2ikmjtmoJbDBT1b7nHvFCdU=
-google.golang.org/genproto/googleapis/rpc v0.0.0-20250224174004-546df14abb99 h1:ZSlhAUqC4r8TPzqLXQ0m3upBNZeF+Y8jQ3c4CR3Ujms=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20250425173222-7b384671a197 h1:29cjnHVylHwTzH66WfFZqgSQgnxzvWE+jvBwpZCLRxY=
-google.golang.org/genproto/googleapis/rpc v0.0.0-20250224174004-546df14abb99/go.mod h1:LuRYeWDFV6WOn90g357N17oMCaxpgCnbi/44qJvDn2I=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20250425173222-7b384671a197/go.mod h1:qQ0YXyHHx3XkvlzUtpXDkS29lDSafHMZBAZDc03LQ3A=
-google.golang.org/grpc v1.70.0 h1:pWFv03aZoHzlRKHWicjsZytKAiYCtNS0dHbXnIdq7jQ=
+google.golang.org/grpc v1.72.0 h1:S7UkcVa60b5AAQTaO6ZKamFp1zMZSU0fGDK2WZLbBnM=
-google.golang.org/grpc v1.70.0/go.mod h1:ofIJqVKDXx/JiXrwr2IG4/zwdH9txy3IlF40RmcJSQw=
+google.golang.org/grpc v1.72.0/go.mod h1:wH5Aktxcg25y1I3w7H69nHfXdOG3UiadoBtjh3izSDM=
-google.golang.org/protobuf v1.36.5 h1:tPhr+woSbjfYvY6/GPufUoYizxw1cF/yFoxJ2fmpwlM=
+google.golang.org/protobuf v1.36.6 h1:z1NpPI8ku2WgiWnf+t9wTPsn6eP1L7ksHUlkfLvd9xY=
-google.golang.org/protobuf v1.36.5/go.mod h1:9fA7Ob0pmnwhb644+1+CVWFRbNajQ6iRojtC/QF5bRE=
+google.golang.org/protobuf v1.36.6/go.mod h1:jduwjTPXsFjZGTmRluh+L6NjiWu7pchiJ2/5YcXBHnY=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=

grpc.go

@@ -74,22 +74,24 @@ func (g *grpcClient) secure(addr string) grpc.DialOption {
 }
 
 func (g *grpcClient) call(ctx context.Context, addr string, req client.Request, rsp interface{}, opts client.CallOptions) error {
-	var header map[string][]string
+	var header gmetadata.MD
 
 	if md, ok := metadata.FromOutgoingContext(ctx); ok {
-		header = metadata.Copy(md)
+		header = metadata.Copy(md).AsHTTP2()
 	} else {
-		header = make(map[string][]string, 2)
+		header = make(gmetadata.MD, 4)
 	}
 	if opts.RequestMetadata != nil {
 		for k, v := range opts.RequestMetadata {
-			header[k] = v
+			header[strings.ToLower(k)] = v
 		}
 	}
 	// set timeout in nanoseconds
-	header["grpc-timeout"] = append(header["grpc-timeout"], fmt.Sprintf("%dn", opts.RequestTimeout))
+	if opts.RequestTimeout > time.Duration(0) {
-	header["timeout"] = append(header["timeout"], fmt.Sprintf("%dn", opts.RequestTimeout))
+		header.Set("grpc-timeout", fmt.Sprintf("%dn", opts.RequestTimeout))
-	header["content-type"] = append(header["content-type"], req.ContentType())
+		header.Set("timeout", fmt.Sprintf("%dn", opts.RequestTimeout))
+	}
+	header.Set("content-type", req.ContentType())
 
 	ctx = gmetadata.NewOutgoingContext(ctx, header)
 
@@ -185,21 +187,19 @@ func (g *grpcClient) call(ctx context.Context, addr string, req client.Request,
 }
 
 func (g *grpcClient) stream(ctx context.Context, addr string, req client.Request, rsp interface{}, opts client.CallOptions) error {
-	var header map[string][]string
+	var header gmetadata.MD
 
 	if md, ok := metadata.FromOutgoingContext(ctx); ok {
-		header = metadata.Copy(md)
+		header = metadata.Copy(md).AsHTTP2()
 	} else {
-		header = make(map[string][]string)
+		header = make(gmetadata.MD, 4)
 	}
 
-	// set timeout in nanoseconds
+	if opts.RequestTimeout > time.Duration(0) {
-	if opts.StreamTimeout > time.Duration(0) {
+		header.Set("grpc-timeout", fmt.Sprintf("%dn", opts.RequestTimeout))
-		header["grpc-timeout"] = append(header["grpc-timeout"], fmt.Sprintf("%dn", opts.RequestTimeout))
+		header.Set("timeout", fmt.Sprintf("%dn", opts.RequestTimeout))
-		header["timeout"] = append(header["timeout"], fmt.Sprintf("%dn", opts.RequestTimeout))
 	}
-	// set the content type for the request
+	header.Set("content-type", req.ContentType())
-	header["content-type"] = append(header["content-type"], req.ContentType())
 
 	ctx = gmetadata.NewOutgoingContext(ctx, header)