Generate pom file (#83)

The `build-java` job also generates and archives the pom file.
 
# Checklist

The following aspects have been respected by the author of this pull
request, confirmed by both pull request assignee **and** reviewer:

* Changelog update (necessity checked and entry added or not added
respectively)
  * [x] Pull Request Assignee
  * [x] Reviewer
* README update (necessity checked and entry added or not added
respectively)
  * [x] Pull Request Assignee
  * [x] Reviewer

.github/workflows/build-java.yml

@@ -40,12 +40,20 @@ jobs:
           gradle-version: ${{ env.GRADLE_VERSION }}
       - name: Execute build
         working-directory: ./java
-        run: ./gradlew jar
-      - name: Archive built jars
+        run: ./gradlew jar generatePomFileForMavenPublication
+      - name: Rename pom file for release
+        if: startsWith(github.ref, 'refs/tags/v')
+        working-directory: ./java/build/publications/maven
+        run: mv pom-default.xml ./../../libs/t2iapi-${{ env.BASE_PACKAGE_VERSION }}.pom
+      - name: Rename pom file for snapshot
+        if: ${{ !startsWith(github.ref, 'refs/tags/v') }}
+        working-directory: ./java/build/publications/maven
+        run: mv pom-default.xml ./../../libs/t2iapi-${{ env.BASE_PACKAGE_VERSION }}.${{ github.run_number }}-SNAPSHOT.pom
+      - name: Archive built jars and pom
         uses: actions/upload-artifact@v4
         with:
           name: target_jars
-          path: java/build/libs/*.jar
+          path: java/build/libs
   run-tests-java17:
     runs-on: ubuntu-latest
     needs: build-java