Upgrade to Java 17 baseline

Closes gh-1945

Author: eleftherias

.github/workflows/continuous-integration-workflow.yml

@@ -22,7 +22,7 @@ jobs:
     if: github.repository == 'spring-projects/spring-session'
     strategy:
       matrix:
-        jdk: [8, 11]
+        jdk: [17]
       fail-fast: false
     steps:
       - uses: actions/checkout@v2
@@ -55,7 +55,7 @@ jobs:
       - name: Set up JDK
         uses: actions/setup-java@v1
         with:
-          java-version: '8'
+          java-version: '17'
       - name: Setup gradle user name
         run: |
           mkdir -p ~/.gradle
@@ -83,7 +83,7 @@ jobs:
       - name: Set up JDK
         uses: actions/setup-java@v1
         with:
-          java-version: '8'
+          java-version: '17'
       - name: Setup gradle user name
         run: |
           mkdir -p ~/.gradle

.github/workflows/pr-build-workflow.yml

@@ -9,7 +9,7 @@ jobs:
     if: github.repository == 'spring-projects/spring-session'
     strategy:
       matrix:
-        jdk: [8, 11]
+        jdk: [17]
       fail-fast: false
     steps:
       - uses: actions/checkout@v2

build.gradle

@@ -35,7 +35,7 @@ subprojects {
 	apply plugin: 'io.spring.javaformat'
 
 	plugins.withType(JavaPlugin) {
-		sourceCompatibility = JavaVersion.VERSION_1_8
+		sourceCompatibility = JavaVersion.VERSION_17
 	}
 
 	tasks.withType(Test) {

buildSrc/build.gradle

@@ -4,7 +4,7 @@ plugins {
     id "groovy"
 }
 
-sourceCompatibility = 1.8
+sourceCompatibility = JavaVersion.VERSION_17
 
 repositories {
     jcenter()

buildSrc/src/main/groovy/io/spring/gradle/convention/JacocoPlugin.groovy

@@ -34,7 +34,7 @@ class JacocoPlugin implements Plugin<Project> {
 			project.tasks.check.dependsOn project.tasks.jacocoTestReport
 
 			project.jacoco {
-				toolVersion = '0.8.2'
+				toolVersion = '0.8.7'
 			}
 		}
 	}

buildSrc/src/test/java/io/spring/gradle/convention/JavadocApiPluginITest.java

@@ -28,7 +28,7 @@ public void multiModuleApi() throws Exception {
 				.build();
 		assertThat(result.task(":api").getOutcome()).isEqualTo(TaskOutcome.SUCCESS);
         File allClasses = new File(testKit.getRootDir(), "build/api/allclasses-noframe.html");
-		File index = new File(testKit.getRootDir(), "build/api/allclasses.html");
+		File index = new File(testKit.getRootDir(), "build/api/allclasses-index.html");
 		File listing = allClasses.exists() ? allClasses : index;
 		String listingText = FileUtils.readFileToString(listing);
 		assertThat(listingText).contains("sample/Api.html");