Upgrade build for Java 17 as base Java version

* Configure maven-enforcer-plugin to require Java 17

* Configure maven-enforcer-plugin to require maven 3.8+ as
  done in GeoServer.

* Upgrade github actions workflows to use Java 17

* Remove cobertura-maven-plugin (modules/extension/xsd/**), as it is not
  compatible with Java 11

* Update maven-javadoc-plugin configuration to use legacyMode=true and not
  fail due to module-info.java not present.

* Plugin version upgrades:
  * jacoco 0.8.7 -> 0.8.13
  * maven-checkstyle-plugin 3.3.0 -> 3.6.0
  * maven-compiler-plugin 3.11.0 -> 3.14.0
  * maven-javadoc-plugin 3.6.3 -> 3.11.2

* Add .mvn/jvm.config with necessary --add-exports and --add-opens
  for internal jdk.compiler packages.

  This ensures that build-time tools and compiler plugins interacting
  with javac internals can function correctly under Java 17's module system.

* Centralize maven plugin versions in the root pom's pluginManagement
  section.

Author: groldan

.github/workflows/azure-integration.yml

@@ -22,7 +22,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        java-version: [ 11, 17, 21 ]
+        java-version: [ 17, 21 ]
     steps:
     - uses: actions/checkout@v4
     - uses: actions/setup-java@v3
@@ -57,7 +57,7 @@ jobs:
     - uses: actions/setup-java@v3
       with:
         distribution: 'temurin'
-        java-version: 11
+        java-version: 17
         cache: 'maven'
 
     - name: Tests against Azure

.github/workflows/integration.yml

@@ -16,10 +16,10 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - name: Set up JDK 11
+    - name: Set up JDK 17
       uses: actions/setup-java@v3
       with:
-        java-version: 11
+        java-version: 17
         distribution: 'temurin'
     - uses: actions/checkout@v4
     - name: Maven repository caching

.github/workflows/linux.yml

@@ -10,28 +10,6 @@ env:
   MAVEN_OPTS: -Dmaven.wagon.httpconnectionManager.ttlSeconds=120 -Dmaven.wagon.http.retryHandler.count=3 -Xmx512m -Djava.awt.headless=true -Dorg.slf4j.simpleLogger.showDateTime=true -Dorg.slf4j.simpleLogger.dateTimeFormat=HH:mm:ss,SSS
 
 jobs:
-  openjdk11:
-    runs-on: [ubuntu-22.04]
-    steps:
-    - uses: actions/checkout@v4
-    - name: Set up JDK 11
-      uses: actions/setup-java@v3
-      with:
-        java-version: 11
-        distribution: 'temurin'
-    - name: Maven repository caching
-      uses: actions/cache@v3
-      with:
-        path: ~/.m2/repository
-        key: gwc-${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}
-        restore-keys: |
-          ${{ runner.os }}-maven-
-    - name: Build with Maven
-      run: mvn -B clean install -Dspotless.apply.skip=true -Dall -T2 --file geowebcache/pom.xml
-    - name: Remove SNAPSHOT jars from repository
-      run: |
-        find .m2/repository -name "*SNAPSHOT*" -type d | xargs rm -rf {}
-
   openjdk17:
     runs-on: [ubuntu-22.04]
     steps:
@@ -80,10 +58,10 @@ jobs:
     runs-on: [ubuntu-22.04]
     steps:
     - uses: actions/checkout@v4
-    - name: Set up JDK 11
+    - name: Set up JDK 17
       uses: actions/setup-java@v3
       with:
-        java-version: 11
+        java-version: 17
         distribution: 'temurin'
     - name: Maven repository caching
       uses: actions/cache@v3

.github/workflows/macos.yml

@@ -13,10 +13,10 @@ jobs:
 
     steps:
     - uses: actions/checkout@v4
-    - name: Set up JDK 11
+    - name: Set up JDK 17
       uses: actions/setup-java@v3
       with:
-        java-version: 11
+        java-version: 17
         distribution: 'temurin'
     - name: Maven repository caching
       uses: actions/cache@v3

.github/workflows/windows.yml

@@ -13,10 +13,10 @@ jobs:
 
     steps:
     - uses: actions/checkout@v4
-    - name: Set up JDK 11
+    - name: Set up JDK 17
       uses: actions/setup-java@v3
       with:
-        java-version: 11
+        java-version: 17
         distribution: 'temurin'
     - name: Maven repository caching
       uses: actions/cache@v3