ci: upgrade workflows to Java 23

.github/workflows/pull_request.yml

@@ -27,7 +27,7 @@ jobs:
           - os: ubuntu-latest
             java-version: 17
           - os: ubuntu-latest
-            java-version: 22
+            java-version: 23
     timeout-minutes: 120
     steps:
       - uses: actions/checkout@v4
@@ -54,7 +54,7 @@ jobs:
           - os: ubuntu-latest
             java-version: 17
           - os: ubuntu-latest
-            java-version: 22
+            java-version: 23
     timeout-minutes: 120
     steps:
       - uses: actions/checkout@v4
@@ -97,7 +97,7 @@ jobs:
       matrix:
         os: [ ubuntu-latest ] # Windows doesn't work, Mac is not a deploy OS.
         module: ["spring-integration", "quarkus-integration"]
-        java-version: [ 17, 21, 22 ] # LTS + latest.
+        java-version: [ 17, 21, 23 ] # LTS + latest.
     timeout-minutes: 120
     steps:
       - uses: actions/checkout@v4

.github/workflows/pull_request_quickstarts.yml

@@ -74,7 +74,7 @@ jobs:
     strategy:
       matrix:
         os: [ ubuntu-latest ]
-        java-version: [ 17 ] # Only the first supported LTS; already too many jobs here.
+        java-version: [ 21 ] # Only the latest supported LTS; already too many jobs here.
         # TODO: Add Python 3.10 once employee scheduling and school timetabling support it
         python-version: ['3.11', '3.12']
       fail-fast: false

.github/workflows/pull_request_secure.yml

@@ -225,10 +225,10 @@ jobs:
           fetch-depth: 0 # Otherwise merge will fail on account of not having history.
 
       # Build and test
-      - name: Set up JDK 17
+      - name: Set up the JDK
         uses: actions/setup-java@v4
         with:
-          java-version: 17
+          java-version: 21
           distribution: 'temurin'
           cache: 'maven'
 

.github/workflows/release.yml

@@ -60,7 +60,7 @@ jobs:
 
       - uses: actions/setup-java@v4
         with:
-          java-version: '17'
+          java-version: '21'
           distribution: 'temurin'
           cache: 'maven'