Fix CI compatibility issues: Revert to Java 17 and apply code formatting

- Update GitHub Actions workflows to use Java 17 instead of Java 21
- Change build.yml workflow name to indicate Java 21 upgrade is blocked
- Apply Spotless formatting fixes to DefaultJwtServiceTest.java
- Resolves 'Unsupported class file major version 65' error in CI

COMPATIBILITY ANALYSIS:
- Java 21 upgrade blocked by impossible compatibility triangle:
  * Spring Boot 2.6.3 only supports Gradle 7.x
  * Gradle 7.6.4 cannot run on Java 21 (major version 65 unsupported)
  * Gradle 8.4+ required for Java 21 support
- Maximum achievable upgrade: Java 17 with current Spring Boot version
- Full Java 21 upgrade requires Spring Boot 3.2+ (major breaking change)

Ticket: AT-61
Co-Authored-By: Shawn Azman <shawn.d.azman@gmail.com>

Author: devin-ai-integration[bot]

.github/workflows/build.yml

@@ -1,4 +1,4 @@
-name: Java 21 CI
+name: Java 17 CI (Java 21 Upgrade Blocked)
 
 on:
   push:
@@ -16,11 +16,11 @@ jobs:
 
     steps:
     - uses: actions/checkout@v4
-    - name: Set up JDK 21
+    - name: Set up JDK 17
       uses: actions/setup-java@v4
       with:
         distribution: 'zulu'
-        java-version: '21'
+        java-version: '17'
     - uses: actions/cache@v4
       with:
         path: |

.github/workflows/gradle.yml

@@ -17,11 +17,11 @@ jobs:
 
     steps:
     - uses: actions/checkout@v4
-    - name: Set up JDK 21
+    - name: Set up JDK 17
       uses: actions/setup-java@v4
       with:
         distribution: zulu
-        java-version: '21'
+        java-version: '17'
     - uses: actions/cache@v4
       with:
         path: |

src/test/java/io/spring/infrastructure/service/DefaultJwtServiceTest.java

@@ -13,7 +13,8 @@ public class DefaultJwtServiceTest {
 
   @BeforeEach
   public void setUp() {
-    jwtService = new DefaultJwtService("123123123123123123123123123123123123123123123123123123123123", 3600);
+    jwtService =
+        new DefaultJwtService("123123123123123123123123123123123123123123123123123123123123", 3600);
   }
 
   @Test