Give the native jobs a JDK 21, which Gradle does not find on Windows

The Windows job failed in :open-java-format-spi:compileJava: no Java installation matched languageVersion=21. The jars compile with a Java 21 toolchain, and the native jobs set up only GraalVM 25. On Linux and macOS Gradle found the runner's preinstalled JDK 21 by its location, which hid the gap; on Windows it looks for JDKs in the registry, where the runner's are not. gradle.properties already names JDK21_HOME as the place to look, so the native jobs of both workflows now install a Temurin 21 and pass its path there. It comes before GraalVM, so that Gradle itself still runs on GraalVM 25. The same failure, reproduced locally with auto-detection off, goes away with JDK21_HOME set.

Author: abashev

.github/workflows/ci.yml

@@ -65,6 +65,16 @@ jobs:
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
+      # The jars compile with a Java 21 toolchain, which gradle.properties looks up in JDK21_HOME. On
+      # Linux and macOS Gradle also finds the runner's own JDK 21 by its location, on Windows it does not.
+      # Installed before GraalVM, so that Gradle itself still runs on GraalVM.
+      - name: Install JDK 21 for the jars
+        id: jdk21
+        uses: actions/setup-java@de7274f081f381c8f8158605e0321c36c376e2e6 # v6.0.1
+        with:
+          distribution: temurin
+          java-version: '21'
+
       - name: Install GraalVM 25 for the image
         uses: graalvm/setup-graalvm@5298d94fb55a4f185c602eeac5de1b553882abe2 # v1.6.4
         with:
@@ -74,6 +84,8 @@ jobs:
 
       - name: Compile the native image
         run: ./gradlew -PnativeImage=true :open-java-format-native:nativeCompile
+        env:
+          JDK21_HOME: ${{ steps.jdk21.outputs.path }}
 
       # The binary itself on a file that needs formatting, a formatted one and one that does not parse.
       # For the Windows binary this is the only check.
@@ -94,6 +106,8 @@ jobs:
       - name: Test the plugins against the image
         if: runner.os != 'Windows'
         run: ./gradlew -PnativeImage=true :open-java-format-jdk-bootstrap:test :gradle-open-java-format:test
+        env:
+          JDK21_HOME: ${{ steps.jdk21.outputs.path }}
 
       - name: Publish Test Report
         uses: mikepenz/action-junit-report@a9170d5795813c01ab4901ffb045b52bab4ab09d # v6.5.0

.github/workflows/release.yml

@@ -85,6 +85,15 @@ jobs:
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
+      # The Java 21 toolchain for the jars, through JDK21_HOME, as in ci.yml: Gradle does not find the
+      # runner's own JDK 21 on Windows. Installed before GraalVM, so that Gradle still runs on GraalVM.
+      - name: Install JDK 21 for the jars
+        id: jdk21
+        uses: actions/setup-java@de7274f081f381c8f8158605e0321c36c376e2e6 # v6.0.1
+        with:
+          distribution: temurin
+          java-version: '21'
+
       - name: Install GraalVM 25 for the image
         uses: graalvm/setup-graalvm@5298d94fb55a4f185c602eeac5de1b553882abe2 # v1.6.4
         with:
@@ -94,6 +103,8 @@ jobs:
 
       - name: Compile the native image
         run: ./gradlew -PnativeImage=true :open-java-format-native:nativeCompile
+        env:
+          JDK21_HOME: ${{ steps.jdk21.outputs.path }}
 
       - name: Hand the binary to the deploy job
         uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1