Use JDK 21 for release (#962)

.github/workflows/publish-release.yml

@@ -16,12 +16,12 @@ jobs:
     steps:
       - uses: actions/checkout@v3
 
-      - id: setup-jdk-17
-        name: Set up JDK 17
+      - id: setup-jdk-21
+        name: Set up JDK 21
         uses: actions/setup-java@v3
         with:
           distribution: 'temurin'
-          java-version: '17'
+          java-version: '21'
 
       - name: Setup Gradle
         uses: gradle/gradle-build-action@v2

.github/workflows/publish-site.yml

@@ -19,12 +19,12 @@ jobs:
         run: |
           sudo apt-get -y install graphviz
 
-      - id: setup-jdk-17
-        name: Set up JDK 17
+      - id: setup-jdk-21
+        name: Set up JDK 21
         uses: actions/setup-java@v3
         with:
           distribution: 'temurin'
-          java-version: '17'
+          java-version: '21'
 
       - name: Setup Gradle
         uses: gradle/gradle-build-action@v2

.github/workflows/tag-new-release.yml

@@ -49,12 +49,12 @@ jobs:
           git_user_signingkey: true
           git_commit_gpgsign: true
 
-      - id: setup-jdk-17
-        name: Set up JDK 17
+      - id: setup-jdk-21
+        name: Set up JDK 21
         uses: actions/setup-java@v3
         with:
           distribution: 'temurin'
-          java-version: '17'
+          java-version: '21'
 
       - name: Set up Gradle
         uses: gradle/gradle-build-action@v2

build.gradle

@@ -141,6 +141,6 @@ allprojects {
 // Require to use JDK 21 when releasing.
 tasks.release.doFirst {
     if (JavaVersion.current() != JavaVersion.VERSION_21) {
-        throw new IllegalStateException("You must release using JDK 17.")
+        throw new IllegalStateException("You must release using JDK 21. Current: ${JavaVersion.current()}")
     }
 }