Upgrade to Java 17

Closes spring-projectsgh-832

Author: jgrandja

README.adoc

@@ -52,9 +52,9 @@ In the instructions below, https://vimeo.com/34436402[`./gradlew`] is invoked fr
 a cross-platform, self-contained bootstrap mechanism for the build.
 
 === Prerequisites
-https://help.github.com/set-up-git-redirect[Git] and the https://www.oracle.com/technetwork/java/javase/downloads[JDK8 build].
+https://help.github.com/set-up-git-redirect[Git] and the https://www.oracle.com/technetwork/java/javase/downloads[JDK17 build].
 
-Be sure that your `JAVA_HOME` environment variable points to the `jdk1.8.0` folder extracted from the JDK download.
+Be sure that your `JAVA_HOME` environment variable points to the `jdk17` folder extracted from the JDK download.
 
 === Check out sources
 [indent=0]

buildSrc/build.gradle

@@ -4,7 +4,7 @@ plugins {
 	id "groovy"
 }
 
-sourceCompatibility = JavaVersion.VERSION_1_8
+sourceCompatibility = JavaVersion.VERSION_17
 
 repositories {
 	gradlePluginPortal()

buildSrc/src/main/java/org/springframework/gradle/SpringJavaPlugin.java

@@ -73,15 +73,15 @@ public void apply(Project project) {
 
 		// Apply Java source compatibility version
 		JavaPluginExtension java = project.getExtensions().getByType(JavaPluginExtension.class);
-		java.setTargetCompatibility(JavaVersion.VERSION_1_8);
+		java.setTargetCompatibility(JavaVersion.VERSION_17);
 
 		// Configure Java tasks
 		project.getTasks().withType(JavaCompile.class, (javaCompile) -> {
 			CompileOptions options = javaCompile.getOptions();
 			options.setEncoding("UTF-8");
 			options.getCompilerArgs().add("-parameters");
 			if (JavaVersion.current().isJava11Compatible()) {
-				options.getRelease().set(8);
+				options.getRelease().set(17);
 			}
 		});
 		project.getTasks().withType(Jar.class, (jar) -> jar.manifest((manifest) -> {

buildSrc/src/main/java/org/springframework/gradle/docs/SpringJavadocApiPlugin.java

@@ -54,7 +54,7 @@ public void apply(Project project) {
 		api.doLast(new Action<Task>() {
 			@Override
 			public void execute(Task task) {
-				if (JavaVersion.current().isJava8Compatible()) {
+				if (JavaVersion.current().isCompatibleWith(JavaVersion.VERSION_17)) {
 					project.copy((copy) -> copy.from(api.getDestinationDir())
 							.into(api.getDestinationDir())
 							.include("element-list")

docs/src/docs/asciidoc/examples/spring-authorization-server-docs-examples.gradle

@@ -4,7 +4,7 @@ plugins {
 
 group = project.rootProject.group
 version = project.rootProject.version
-sourceCompatibility = "1.8"
+sourceCompatibility = "17"
 
 repositories {
 	mavenCentral()

docs/src/docs/asciidoc/getting-started.adoc

@@ -6,7 +6,7 @@ If you are just getting started with Spring Authorization Server, the following
 [[system-requirements]]
 == System Requirements
 
-Spring Authorization Server requires a Java 8 or higher Runtime Environment.
+Spring Authorization Server requires a Java 17 or higher Runtime Environment.
 
 [[installing-spring-authorization-server]]
 == Installing Spring Authorization Server

samples/custom-consent-authorizationserver/samples-custom-consent-authorizationserver.gradle

@@ -6,7 +6,7 @@ plugins {
 
 group = project.rootProject.group
 version = project.rootProject.version
-sourceCompatibility = "1.8"
+sourceCompatibility = "17"
 
 repositories {
 	mavenCentral()

samples/default-authorizationserver/samples-default-authorizationserver.gradle

@@ -6,7 +6,7 @@ plugins {
 
 group = project.rootProject.group
 version = project.rootProject.version
-sourceCompatibility = "1.8"
+sourceCompatibility = "17"
 
 repositories {
 	mavenCentral()

samples/federated-identity-authorizationserver/samples-federated-identity-authorizationserver.gradle

@@ -6,7 +6,7 @@ plugins {
 
 group = project.rootProject.group
 version = project.rootProject.version
-sourceCompatibility = "1.8"
+sourceCompatibility = "17"
 
 repositories {
 	mavenCentral()

samples/messages-client/samples-messages-client.gradle

@@ -6,7 +6,7 @@ plugins {
 
 group = project.rootProject.group
 version = project.rootProject.version
-sourceCompatibility = "1.8"
+sourceCompatibility = "17"
 
 repositories {
 	mavenCentral()

samples/messages-resource/samples-messages-resource.gradle

@@ -6,7 +6,7 @@ plugins {
 
 group = project.rootProject.group
 version = project.rootProject.version
-sourceCompatibility = "1.8"
+sourceCompatibility = "17"
 
 repositories {
 	mavenCentral()