Upgrade to Java 21 and update Docker base images accordingly

.claude/settings.local.json

@@ -8,7 +8,12 @@
       "Bash(rm -f /Users/thilo/development/java/JavadocViewerService/database/jvsdb.mv.db /Users/thilo/development/java/JavadocViewerService/database/jvsdb.trace.db)",
       "Bash(mvn spring-boot:run)",
       "Bash(mvn spring-boot:run -Dspring-boot.run.jvmArguments=\"-Ddebug=true\")",
-      "Bash(jar tf:*)"
+      "Bash(jar tf:*)",
+      "Bash(mvn dependency:tree)",
+      "Bash(sdk use:*)",
+      "Bash(mvn clean:*)",
+      "Bash(source \"$HOME/.sdkman/bin/sdkman-init.sh\")",
+      "Bash(sed -i '' 's/<java.version>21</<java.version>17</' pom.xml)"
     ]
   }
 }

Dockerfile

@@ -1,5 +1,5 @@
 # Stage 1: Build the JAR using Maven
-FROM maven:3.9-eclipse-temurin-17 AS builder
+FROM maven:3.9-eclipse-temurin-21 AS builder
 
 LABEL org.opencontainers.image.description="JavadocViewerService serves and manages Javadoc documentation from Git repositories."
 
@@ -14,7 +14,7 @@ COPY src ./src
 RUN mvn clean package -DskipTests
 
 # Stage 2: Minimal runtime image
-FROM eclipse-temurin:17-jdk-jammy
+FROM eclipse-temurin:21-jdk-jammy
 
 WORKDIR /app
 

pom.xml

@@ -18,7 +18,7 @@
     </parent>
 
     <properties>
-        <java.version>17</java.version>
+        <java.version>21</java.version>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     </properties>
 
@@ -80,7 +80,7 @@
         <dependency>
             <groupId>org.eclipse.jgit</groupId>
             <artifactId>org.eclipse.jgit</artifactId>
-            <version>6.6.1.202309021850-r</version>
+            <version>7.2.1.202505142326-r</version>
         </dependency>
         <dependency>
             <groupId>com.fasterxml.jackson.dataformat</groupId>