diff --git a/.github/workflows/pull_request.yml b/.github/workflows/pull_request.yml
index 5be96f44c5..e102b99610 100644
--- a/.github/workflows/pull_request.yml
+++ b/.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
diff --git a/.github/workflows/pull_request_quickstarts.yml b/.github/workflows/pull_request_quickstarts.yml
index 25bd50a4fc..f558a63baf 100644
--- a/.github/workflows/pull_request_quickstarts.yml
+++ b/.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
diff --git a/.github/workflows/pull_request_secure.yml b/.github/workflows/pull_request_secure.yml
index 5a45153f3c..a2e6f42b1b 100644
--- a/.github/workflows/pull_request_secure.yml
+++ b/.github/workflows/pull_request_secure.yml
@@ -70,10 +70,10 @@ jobs:
           path: ./timefold-solver
           ref: ${{ github.event.pull_request.head.sha }} # The GHA event will pull the main branch by default, and we must specify the PR reference version
 
-      - name: Setup Temurin 21 and Maven
+      - name: Setup Temurin 17 and Maven
         uses: actions/setup-java@v4
         with:
-          java-version: '21'
+          java-version: '17'
           distribution: 'temurin'
           cache: 'maven'
 
@@ -172,10 +172,10 @@ jobs:
           fetch-depth: 0 # Otherwise merge will fail on account of not having history.
 
       # Build and test
-      - name: Setup Temurin 21 and Maven
+      - name: Setup Temurin 17 and Maven
         uses: actions/setup-java@v4
         with:
-          java-version: '21'
+          java-version: '17'
           distribution: 'temurin'
           cache: 'maven'
       - name: Quickly build timefold-solver
@@ -225,7 +225,7 @@ 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
@@ -266,10 +266,10 @@ jobs:
         with:
           fetch-depth: 0  # Shallow clones should be disabled for a better relevancy of analysis
           ref: ${{ github.event.pull_request.head.sha }} # The GHA event will pull the main branch by default, and we must specify the PR reference version
-      - name: Set up JDK 21
+      - name: Set up JDK 17
         uses: actions/setup-java@v4
         with:
-          java-version: 21
+          java-version: 17
           distribution: 'temurin'
           cache: 'maven'
       - name: Python 3.10, Python 3.11, Python 3.12 Setup
diff --git a/migration/pom.xml b/migration/pom.xml
index 99ec50cc40..0c9928022c 100644
--- a/migration/pom.xml
+++ b/migration/pom.xml
@@ -60,6 +60,11 @@
       <artifactId>rewrite-java-17</artifactId>
       <scope>runtime</scope>
     </dependency>
+    <dependency>
+      <groupId>org.openrewrite</groupId> <!-- Does not break Java 17 compatibility. -->
+      <artifactId>rewrite-java-21</artifactId>
+      <scope>runtime</scope>
+    </dependency>
     <dependency>
       <groupId>org.openrewrite</groupId>
       <artifactId>rewrite-properties</artifactId>