Enable syntax highlighting for javadoc code blocks using JDK 25

Upgrade javadoc toolchain from JDK 23 to JDK 25 to use the new
`--syntax-highlight` option, which bundles highlight.js for automatic
syntax highlighting of fenced code blocks in markdown documentation.

- Update `javadoc.jdk.version` from 23 to 25 in `pom.xml`
- Add `--syntax-highlight` option to maven-javadoc-plugin configuration
- Update CI workflows to set up JDK 25 for javadoc generation
- Update contributor documentation with syntax highlighting details

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: jonathanhefner

.github/workflows/ci.yml

@@ -12,10 +12,10 @@ jobs:
       - name: Checkout source code
         uses: actions/checkout@v4
 
-      - name: Set up JDK 23 for Javadoc toolchain
+      - name: Set up JDK 25 for Javadoc toolchain
         uses: actions/setup-java@v4
         with:
-          java-version: '23'
+          java-version: '25'
           distribution: 'temurin'
 
       - name: Set up JDK 17

.github/workflows/maven-central-release.yml

@@ -9,10 +9,10 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      - name: Set up JDK 23 for Javadoc toolchain
+      - name: Set up JDK 25 for Javadoc toolchain
         uses: actions/setup-java@v4
         with:
-          java-version: '23'
+          java-version: '25'
           distribution: 'temurin'
 
       - name: Set up JDK 17

.github/workflows/publish-snapshot.yml

@@ -12,10 +12,10 @@ jobs:
       - name: Checkout source code
         uses: actions/checkout@v4
 
-      - name: Set up JDK 23 for Javadoc toolchain
+      - name: Set up JDK 25 for Javadoc toolchain
         uses: actions/setup-java@v4
         with:
-          java-version: '23'
+          java-version: '25'
           distribution: 'temurin'
 
       - name: Set up JDK 17

pom.xml

@@ -76,7 +76,7 @@
 		<maven-surefire-plugin.version>3.1.2</maven-surefire-plugin.version>
 		<maven-failsafe-plugin.version>3.5.2</maven-failsafe-plugin.version>
 		<maven-javadoc-plugin.version>3.11.2</maven-javadoc-plugin.version>
-		<javadoc.jdk.version>23</javadoc.jdk.version>
+		<javadoc.jdk.version>25</javadoc.jdk.version>
 		<maven-source-plugin.version>3.3.0</maven-source-plugin.version>
 		<jacoco-maven-plugin.version>0.8.10</jacoco-maven-plugin.version>
 		<flatten-maven-plugin.version>1.5.0</flatten-maven-plugin.version>
@@ -286,6 +286,7 @@
 							<doclint>none</doclint>
 							<additionalOptions>
 								<additionalOption>-Xdoclint:none</additionalOption>
+								<additionalOption>--syntax-highlight</additionalOption>
 							</additionalOptions>
 							<source>${java.version}</source>
 							<quiet>true</quiet>
@@ -313,7 +314,7 @@
 				</plugins>
 			</build>
 		</profile>
-		<!-- CI profile - requires JDK 23 toolchain for markdown support -->
+		<!-- CI profile - requires JDK 25 toolchain for markdown support -->
 		<profile>
 			<id>javadoc-toolchain</id>
 			<activation>

src/main/javadoc/README.md

@@ -16,8 +16,9 @@ Example: `mcp-core/src/main/javadoc/io/modelcontextprotocol/doc-files/getting-st
 
 ## Requirements
 
-- **JDK 23+** is required to generate javadocs with markdown support (JEP 467)
+- **JDK 25+** is required to generate javadocs with markdown and syntax highlighting support
 - Files use CommonMark syntax with GitHub-flavored tables
+- Code blocks with language hints (e.g., ` ```java `) get automatic syntax highlighting
 - Generate docs locally: `mvn -Pjavadoc javadoc:aggregate`
 
 ## Linking to Documentation
@@ -43,7 +44,9 @@ See [Getting Started](io/modelcontextprotocol/doc-files/getting-started.html)
 The javadoc tool supports CommonMark with these extensions:
 
 - GitHub-flavored tables
-- Fenced code blocks with syntax highlighting
+- Fenced code blocks with syntax highlighting (via `--syntax-highlight` option using highlight.js)
 - Links to Java elements: `[text][java.util.List]`
 
+Supported languages for syntax highlighting include Java, JSON, XML, HTML, and Properties.
+
 For full details, see [JEP 467: Markdown Documentation Comments](https://openjdk.org/jeps/467).