Use Java 21 for Sonarcloud plugin (#7622)

Sonarcloud analyzer now requires at least Java 17.

.github/workflows/sonarcloud.yml

@@ -19,12 +19,9 @@ jobs:
         with:
           fetch-depth: 0  # Shallow clones should be disabled for a better relevancy of analysis
           submodules: 'recursive'
-      # For building GeoNetwork, JDK8 is necessary, but for running
-      # the SonarQube plugin, JDK11 is necessary.
-      # So, first install JDK 8, build GeoNetwork, then install JDK11
-      # and run SonarQube:
-      - name: Set up JDK 8
-        uses: actions/[email protected]
+          show-progress: 'false'
+      - name: Set up JDK 11
+        uses: actions/[email protected]
         with:
           java-version: 8
           distribution: 'temurin'
@@ -37,11 +34,13 @@ jobs:
           restore-keys: ${{ runner.os }}-sonar
       - name: Build GN
         run: mvn -B package -DskipTests
-      - name: Set up JDK 11
-        uses: actions/[email protected]
+
+      - name: Set up JDK 21 # Sonarcloud analyzer needs at least JDK 17
+        uses: actions/[email protected]
         with:
           distribution: 'temurin'
-          java-version: '11'
+          java-version: '21'
+          cache: 'maven'
       - name: Analyze with Sonar
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}  # Needed to get PR information, if any