feat: upgrade Java compilation target from 17 to 21

- Update maven.compiler.release from 17 to 21 in pom.xml
- Update CI PR workflow MAIN_JAVA_VER to 21 and simplify test matrix
- Update CI release workflow to use Java 21
- Add Java 21 minimum requirement to README
- Revise Known Issues section for Java 17 hang warning

Implements TC-3969

Assisted-by: Claude Code

Author: soul2zimate

.github/workflows/pr.yml

@@ -14,11 +14,11 @@ jobs:
       checks: write
       pull-requests: write
     env:
-      MAIN_JAVA_VER: 17
+      MAIN_JAVA_VER: 21
       RUN_PYTHON_BIN: ${{ vars.RUN_PYTHON_BIN }}
     strategy:
       matrix:
-        java: [17, 21]
+        java: [21]
     steps:
     - name: Checkout sources
       uses: actions/checkout@v6

.github/workflows/release.yml

@@ -25,10 +25,10 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v6
 
-      - name: Set up Java 17
+      - name: Set up Java 21
         uses: actions/setup-java@v5
         with:
-          java-version: '17'
+          java-version: '21'
           distribution: 'temurin'
           cache: 'maven'
           gpg-private-key: ${{ secrets.GPG_PRIVATE_KEY }}

README.md

@@ -3,6 +3,8 @@
 * Looking for our JavaScript/TypeScript API? Try [Trustify DA JavaScript Client](https://github.com/guacsec/trustify-da-javascript-client).
 * Looking for our Backend implementation? Try [Trustify Dependency Analytics](https://github.com/guacsec/trustify-dependency-analytics).
 
+**Requires Java 21 or later.**
+
 The _Trustify DA Java Client_ module is deployed to _GitHub Package Registry_.
 
 <details>
@@ -824,10 +826,9 @@ Released artifacts are available on [Maven Central](https://repo1.maven.org/mave
 
 
 
-- For maven pom.xml, it has been noticed that using java 17 might cause stack analysis to hang forever.
-  This is caused by maven [`dependency` Plugin](https://maven.apache.org/plugins/maven-dependency-plugin/) bug when running with JDK/JRE' JVM version 17.
-
-  To overcome this, you can use any other java version (14,20,21, etc..). ( best way is to install JDK/JRE version different from 17 , and set the location of the installation in environment variable `JAVA_HOME` so maven will use it.)
+- For maven pom.xml, it has been noticed that using Java 17 might cause stack analysis to hang forever.
+  This is caused by maven [`dependency` Plugin](https://maven.apache.org/plugins/maven-dependency-plugin/) bug when running with JDK/JRE JVM version 17.
+  This project now requires Java 21 as the minimum version, which is not affected by this issue.
 
 
 <!-- Badge links -->

pom.xml

@@ -16,7 +16,7 @@
     <code.coverage.threshold>81%</code.coverage.threshold>
     <mutation.coverage.threshold>50</mutation.coverage.threshold>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-    <maven.compiler.release>17</maven.compiler.release>
+    <maven.compiler.release>21</maven.compiler.release>
     <!-- Dependencies -->
     <trustify-da-api-model.version>2.0.7</trustify-da-api-model.version>
     <jackson.version>2.21.2</jackson.version>