Upgrade to Dokka 2.0.0

See https://kotlinlang.org/docs/dokka-migration.html

Closes gh-35211

Author: sdeleuze

build.gradle

@@ -2,7 +2,7 @@ plugins {
 	id 'io.freefair.aspectj' version '8.13.1' apply false
 	// kotlinVersion is managed in gradle.properties
 	id 'org.jetbrains.kotlin.plugin.serialization' version "${kotlinVersion}" apply false
-	id 'org.jetbrains.dokka' version '1.9.20'
+	id 'org.jetbrains.dokka'
 	id 'com.github.bjornvester.xjc' version '1.8.2' apply false
 	id 'io.github.goooler.shadow' version '8.1.8' apply false
 	id 'me.champeau.jmh' version '0.7.2' apply false

buildSrc/build.gradle

@@ -20,6 +20,7 @@ ext {
 dependencies {
 	checkstyle "io.spring.javaformat:spring-javaformat-checkstyle:${javaFormatVersion}"
 	implementation "org.jetbrains.kotlin:kotlin-gradle-plugin:${kotlinVersion}"
+	implementation "org.jetbrains.dokka:dokka-gradle-plugin:2.0.0"
 	implementation "com.tngtech.archunit:archunit:1.4.0"
 	implementation "org.gradle:test-retry-gradle-plugin:1.6.2"
 	implementation "io.spring.javaformat:spring-javaformat-gradle-plugin:${javaFormatVersion}"

buildSrc/src/main/java/org/springframework/build/KotlinConventions.java

@@ -17,6 +17,10 @@
 package org.springframework.build;
 
 import org.gradle.api.Project;
+import org.gradle.api.tasks.SourceSet;
+import org.gradle.api.tasks.SourceSetContainer;
+import org.jetbrains.dokka.gradle.DokkaExtension;
+import org.jetbrains.dokka.gradle.DokkaPlugin;
 import org.jetbrains.kotlin.gradle.dsl.JvmTarget;
 import org.jetbrains.kotlin.gradle.dsl.KotlinVersion;
 import org.jetbrains.kotlin.gradle.tasks.KotlinCompile;
@@ -28,8 +32,14 @@
 public class KotlinConventions {
 
 	void apply(Project project) {
-		project.getPlugins().withId("org.jetbrains.kotlin.jvm",
-				(plugin) -> project.getTasks().withType(KotlinCompile.class, this::configure));
+		project.getPlugins().withId("org.jetbrains.kotlin.jvm", _ -> {
+			project.getTasks().withType(KotlinCompile.class, this::configure);
+			if (project.getLayout().getProjectDirectory().dir("src/main/kotlin").getAsFile().exists()) {
+				project.getPlugins().apply(DokkaPlugin.class);
+				project.getExtensions().configure(DokkaExtension.class, dokka -> configure(project, dokka));
+				project.project(":framework-api").getDependencies().add("dokka", project);
+			}
+		});
 	}
 
 	private void configure(KotlinCompile compile) {
@@ -49,4 +59,34 @@ private void configure(KotlinCompile compile) {
 		});
 	}
 
+	private void configure(Project project, DokkaExtension dokka) {
+		dokka.getDokkaSourceSets().forEach(sourceSet -> {
+			sourceSet.getSourceRoots().setFrom(project.file("src/main/kotlin"));
+			sourceSet.getClasspath()
+					.from(project.getExtensions()
+							.getByType(SourceSetContainer.class)
+							.getByName(SourceSet.MAIN_SOURCE_SET_NAME)
+							.getOutput());
+			var externalDocumentationLinks = sourceSet.getExternalDocumentationLinks();
+			externalDocumentationLinks.register("spring-framework", spec -> {
+				spec.url("https://docs.spring.io/spring-framework/docs/current/javadoc-api/");
+				spec.packageListUrl("https://docs.spring.io/spring-framework/docs/current/javadoc-api/element-list");
+			});
+			externalDocumentationLinks.register("reactor-core", spec ->
+					spec.url("https://projectreactor.io/docs/core/release/api/"));
+			externalDocumentationLinks.register("reactive-streams", spec ->
+					spec.url("https://www.reactive-streams.org/reactive-streams-1.0.3-javadoc/"));
+			externalDocumentationLinks.register("kotlinx-coroutines", spec ->
+					spec.url("https://kotlinlang.org/api/kotlinx.coroutines/"));
+			externalDocumentationLinks.register("hamcrest", spec ->
+					spec.url("https://javadoc.io/doc/org.hamcrest/hamcrest/2.1/"));
+			externalDocumentationLinks.register("jakarta-servlet", spec -> {
+				spec.url("https://javadoc.io/doc/jakarta.servlet/jakarta.servlet-api/latest/");
+				spec.packageListUrl("https://javadoc.io/doc/jakarta.servlet/jakarta.servlet-api/latest/element-list");
+			});
+			externalDocumentationLinks.register("rsocket-core", spec ->
+					spec.url("https://javadoc.io/static/io.rsocket/rsocket-core/1.1.1/"));
+		});
+	}
+
 }

framework-api/framework-api.gradle

@@ -1,6 +1,7 @@
 plugins {
 	id 'java-platform'
 	id 'io.freefair.aggregate-javadoc' version '8.13.1'
+	id 'org.jetbrains.dokka'
 }
 
 description = "Spring Framework API Docs"
@@ -54,23 +55,19 @@ javadoc {
 	}
 }
 
-/**
- * Produce KDoc for all Spring Framework modules in "build/docs/kdoc"
- */
-rootProject.tasks.dokkaHtmlMultiModule.configure {
-	dependsOn {
-		tasks.named("javadoc")
+dokka {
+	moduleName = "spring-framework"
+	dokkaPublications.html {
+		outputDirectory = project.java.docsDir.dir("kdoc-api")
+		includes.from("$rootProject.rootDir/framework-docs/src/docs/api/dokka-overview.md")
 	}
-	moduleName.set("spring-framework")
-	outputDirectory.set(project.java.docsDir.dir("kdoc-api").get().asFile)
-	includes.from("$rootProject.rootDir/framework-docs/src/docs/api/dokka-overview.md")
 }
 
 /**
  * Zip all Java docs (javadoc & kdoc) into a single archive
  */
 tasks.register('docsZip', Zip) {
-	dependsOn = ['javadoc', rootProject.tasks.dokkaHtmlMultiModule]
+	dependsOn = ['javadoc', 'dokkaGenerate']
 	group = "distribution"
 	description = "Builds -${archiveClassifier} archive containing api and reference " +
 			"for deployment at https://docs.spring.io/spring-framework/docs/."
@@ -83,7 +80,7 @@ tasks.register('docsZip', Zip) {
 	from(javadoc) {
 		into "javadoc-api"
 	}
-	from(rootProject.tasks.dokkaHtmlMultiModule.outputDirectory) {
+	from(project.java.docsDir.dir("kdoc-api")) {
 		into "kdoc-api"
 	}
 }

gradle.properties

@@ -9,3 +9,6 @@ byteBuddyVersion=1.17.6
 
 kotlin.jvm.target.validation.mode=ignore
 kotlin.stdlib.default.dependency=false
+
+org.jetbrains.dokka.experimental.gradle.pluginMode.noWarn=true
+org.jetbrains.dokka.experimental.gradle.pluginMode=V2Enabled

gradle/docs-dokka.gradle

@@ -15,11 +15,6 @@ dependencies {
 	jmh 'net.sf.jopt-simple:jopt-simple'
 }
 
-pluginManager.withPlugin("kotlin") {
-	apply plugin: "org.jetbrains.dokka"
-	apply from: "${rootDir}/gradle/docs-dokka.gradle"
-}
-
 jmh {
 	duplicateClassesStrategy = DuplicatesStrategy.EXCLUDE
 }