Add github workflow

.github/FUNDING.yml

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+# These are supported funding model platforms
+
+github: dhadka # Replace with up to 4 GitHub Sponsors-enabled usernames e.g., [user1, user2]
+patreon: # Replace with a single Patreon username
+open_collective: # Replace with a single Open Collective username
+ko_fi: # Replace with a single Ko-fi username
+tidelift: # Replace with a single Tidelift platform-name/package-name e.g., npm/babel
+community_bridge: # Replace with a single Community Bridge project-name e.g., cloud-foundry
+liberapay: # Replace with a single Liberapay username
+issuehunt: # Replace with a single IssueHunt username
+otechie: # Replace with a single Otechie username
+lfx_crowdfunding: # Replace with a single LFX Crowdfunding project-name e.g., cloud-foundry
+custom: # Replace with up to 4 custom sponsorship URLs e.g., ['link1', 'link2']

.github/workflows/ci.yml

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+name: CI
+
+on:
+  push:
+  workflow_dispatch:
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        java: [ '16', '17', '18', '19', '20' ]
+    steps:
+      - uses: actions/checkout@v3
+      - name: Set up JDK ${{ matrix.java }}
+        uses: actions/setup-java@v3
+        with:
+          java-version: ${{ matrix.java }}
+          distribution: zulu
+      - run: make
+      - run: mvn test

.github/workflows/stage.yml

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+name: Validate and stage release
+
+on:
+  workflow_dispatch:
+    inputs:
+      version:
+        type: string
+        description: The version to publish
+        required: true
+      publish_github:
+        description: 'Create draft GitHub release'
+        default: true
+        type: boolean
+      publish_maven:
+        description: 'Create Maven bundle'
+        default: true
+        type: boolean
+      skip_validation:
+        description: 'Skip version validations'
+        default: false
+        type: boolean
+
+jobs:
+  stage:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: Set up JDK 16
+        uses: actions/setup-java@v3
+        with:
+          java-version: 16
+          distribution: temurin
+      - name: Install required software
+        run: |
+          sudo apt install xmlstarlet
+      - name: Get project settings
+        run: |
+          shortname=$(xmlstarlet sel -N x="http://maven.apache.org/POM/4.0.0" -t -v "//x:project/x:artifactId/text()" pom.xml)
+          version=$(xmlstarlet sel -N x="http://maven.apache.org/POM/4.0.0" -t -v "//x:project/x:version/text()" pom.xml)
+          echo "BUILD_NAME=${shortname}" >> $GITHUB_ENV
+          echo "BUILD_VERSION=${version}" >> $GITHUB_ENV
+          echo "BUILD_ARTIFACT=${shortname}-${version}" >> $GITHUB_ENV
+      - name: Validate version number
+        if: ${{ ! inputs.skip_validation }}
+        run: |
+          [ "${{ inputs.version }}" == "${BUILD_VERSION}" ] || (>&2 echo "Version does not match value in pom.xml"; exit -1)
+          [ "${{ inputs.version }}" == "$(cat README.md | grep -m 1 '<version>' | tr -d '<>/[:alpha:][:space:]')" ] || (>&2 echo "Version does not match value in README.md"; exit -1)
+      - name: Build artifact
+        run: mvn package javadoc:jar
+      - name: Sign Maven artifacts and create bundle
+        if: ${{ inputs.publish_maven }}
+        run: |
+          echo -n "${GPG_SIGNING_KEY}" | base64 --decode | gpg --import
+
+          mkdir maven
+          cp pom.xml maven/${BUILD_ARTIFACT}.pom
+          cp target/${BUILD_ARTIFACT}.jar maven/
+          cp target/${BUILD_ARTIFACT}-sources.jar maven/
+          cp target/${BUILD_ARTIFACT}-javadoc.jar maven/
+          [ -f "target/${BUILD_ARTIFACT}-jar-with-dependencies.jar" ] && cp target/${BUILD_ARTIFACT}-jar-with-dependencies.jar maven/
+          
+          pushd maven
+          gpg -ab ${BUILD_ARTIFACT}.pom
+          gpg -ab ${BUILD_ARTIFACT}.jar
+          gpg -ab ${BUILD_ARTIFACT}-sources.jar
+          gpg -ab ${BUILD_ARTIFACT}-javadoc.jar
+          [ -f "${BUILD_ARTIFACT}-jar-with-dependencies.jar" ] && gpg -ab ${BUILD_ARTIFACT}-jar-with-dependencies.jar
+          
+          jar -cvf ${BUILD_ARTIFACT}-bundle.jar *
+        env:
+          GPG_SIGNING_KEY: ${{ secrets.GPG_SIGNING_KEY }}
+      - name: Upload Maven bundle
+        if: ${{ inputs.publish_maven }}
+        uses: actions/upload-artifact@v3
+        with:
+          name: Maven bundle
+          path: maven/*-bundle.jar
+      - name: Stage GitHub release
+        if: ${{ inputs.publish_github }}
+        run: |
+          gh release create "v${{ inputs.version }}" --draft --title "Version ${{ inputs.version }}" \
+              target/${BUILD_ARTIFACT}.jar \
+              $([ -f "${BUILD_ARTIFACT}-jar-with-dependencies.jar" ] && echo "target/${BUILD_ARTIFACT}-jar-with-dependencies.jar" || echo "")
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      - name: Upload release artifacts
+        uses: actions/upload-artifact@v3
+        with:
+          name: Release artifacts
+          path: target/*.jar