Define basic GitHub Actions build

.github/workflows/build.yml

@@ -0,0 +1,31 @@
+name: build
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        java: [ '8' ]
+        architecture: [ 'x64' ]
+    name: Build with JDK ${{ matrix.java }} on ${{ matrix.architecture }}
+    steps:
+      - uses: actions/checkout@v4
+      - name: Setup JDK
+        uses: actions/setup-java@v4
+        with:
+          distribution: 'temurin'
+          java-version: ${{ matrix.java }}
+          architecture: ${{ matrix.architecture }}
+          cache: 'gradle'
+
+      - name: Build with Gradle
+        run: ./gradlew asciidoc
+        env:
+          GITHUB_USER: 'foo'

build.gradle

@@ -54,6 +54,9 @@ idea {
     }
 }
 
+githubUser = System.getenv('GITHUB_USER') ?: 'defaultUser'
+githubToken = System.getenv('GITHUB_TOKEN') ?: 'defaultToken'
+
 asciidoctor {
     sourceDir = file('src/docs/asciidoc')
     outputDir = file("$buildDir/docs/asciidoc")