Run tests on JDK 21

Closes gh-13811

(cherry picked from commit 1dcc73a)

.github/workflows/continuous-integration-workflow.yml

@@ -69,21 +69,28 @@ jobs:
   snapshot_tests:
     name: Test against snapshots
     needs: [prerequisites]
+    strategy:
+      matrix:
+        include:
+          - java-version: '21-ea'
+            toolchain: '21'
+          - java-version: '17'
+            toolchain: '17'
     runs-on: ubuntu-latest
     if: needs.prerequisites.outputs.runjobs
     steps:
       - uses: actions/checkout@v3
       - name: Set up gradle
         uses: spring-io/spring-gradle-build-action@v1
         with:
-          java-version: '17'
+          java-version: ${{ matrix.java-version }}
           distribution: 'temurin'
       - name: Snapshot Tests
         run: |
           export GRADLE_ENTERPRISE_CACHE_USERNAME="$GRADLE_ENTERPRISE_CACHE_USER"
           export GRADLE_ENTERPRISE_CACHE_PASSWORD="$GRADLE_ENTERPRISE_CACHE_PASSWORD"
           export GRADLE_ENTERPRISE_ACCESS_KEY="$GRADLE_ENTERPRISE_SECRET_ACCESS_KEY"
-          ./gradlew test --refresh-dependencies -PartifactoryUsername="$ARTIFACTORY_USERNAME" -PartifactoryPassword="$ARTIFACTORY_PASSWORD" -PforceMavenRepositories=snapshot -PspringFrameworkVersion='6.+' -PreactorVersion='2023+' -PspringDataVersion='2023+' -PrsocketVersion=1.1.5-SNAPSHOT -PspringBootVersion='3.+' -PlocksDisabled --stacktrace
+          ./gradlew test --refresh-dependencies -PartifactoryUsername="$ARTIFACTORY_USERNAME" -PartifactoryPassword="$ARTIFACTORY_PASSWORD" -PforceMavenRepositories=snapshot -PtestToolchain=${{ matrix.toolchain }} -PspringFrameworkVersion='6.+' -PreactorVersion='2023+' -PspringDataVersion='2023+' -PrsocketVersion=1.1.5-SNAPSHOT -PspringBootVersion='3.+' -PlocksDisabled --stacktrace
   check_samples:
     name: Check Samples project
     needs: [prerequisites]