fix(java): add GPG signing for Maven Central deployment

Author: renatovico

.github/workflows/release.yml

@@ -316,6 +316,8 @@ jobs:
           server-id: central
           server-username: MAVEN_USERNAME
           server-password: MAVEN_PASSWORD
+          gpg-private-key: ${{ secrets.GPG_PRIVATE_KEY }}
+          gpg-passphrase: GPG_PASSPHRASE
 
       - name: Update version
         run: |
@@ -329,6 +331,7 @@ jobs:
         env:
           MAVEN_USERNAME: ${{ secrets.OSSRH_USERNAME }}
           MAVEN_PASSWORD: ${{ secrets.OSSRH_PASSWORD }}
+          GPG_PASSPHRASE: ${{ secrets.GPG_PASSPHRASE }}
 
   # Publish to crates.io
   publish-crates:

libs/java/pom.xml

@@ -110,7 +110,20 @@
             <id>release</id>
             <build>
                 <plugins>
-                    <!-- No GPG signing required for new Maven Central -->
+                    <plugin>
+                        <groupId>org.apache.maven.plugins</groupId>
+                        <artifactId>maven-gpg-plugin</artifactId>
+                        <version>3.1.0</version>
+                        <executions>
+                            <execution>
+                                <id>sign-artifacts</id>
+                                <phase>verify</phase>
+                                <goals>
+                                    <goal>sign</goal>
+                                </goals>
+                            </execution>
+                        </executions>
+                    </plugin>
                 </plugins>
             </build>
         </profile>