Verify Doc Code Snippets Compile

* Verify Doc Code Snippets Compile
* Move snippets to a new (non-published) sub-project
* Suppress jar creation and publication
* Suppress Regexp checkstyle on Doc Snippets
* Add Java/Kotlin Toggle
* Compile Kotlin Snippets; Fix Checkstyle
* Fix Kotlin Syntax
* Remove runner() from Consumer app.
* Fix missing end tags.
* Topic configuration and other polishing.
* Fix Unused Import.
* Copy Code Snippets into the build dir.
* Fix spurious error messages; copy attributes to build.gradle; move asciidocs to spring-kafka-docs project.
* Fix ToC Synchronization; upgrade spring-doc-resources; add Maven/Gradle Toggle.
* Add `encoding` to `compileTestJava` to make encoding-specific tests OS-independent
* Remove redundant variables from the `index.adoc` since they are set in the plugin config in Gradle
* Fix typo for Kotlin code snippet
* Rework all the Kotlin samples to more Kotlin-idiomatic style
* Fix whitespace.

Co-authored-by: Artem Bilan <abilan@vmware.com>

build.gradle

@@ -42,7 +42,7 @@ ext {
 	linkScmUrl = 'https://github.com/spring-projects/spring-kafka'
 	linkScmConnection = 'https://github.com/spring-projects/spring-kafka.git'
 	linkScmDevConnection = 'git@github.com:spring-projects/spring-kafka.git'
-	docResourcesVersion = '0.2.4'
+	docResourcesVersion = '0.2.5'
 
 
 	if (gitPresent) {
@@ -65,6 +65,7 @@ ext {
 	mockitoVersion = '3.7.0'
 	reactorVersion = '2020.0.3'
 	scalaVersion = '2.13'
+	springBootVersion = '2.4.2' // docs module
 	springDataVersion = '2021.0.0-M2'
 	springRetryVersion = '1.3.0'
 	springVersion = '5.3.3'
@@ -140,6 +141,7 @@ subprojects { subproject ->
 
 	compileTestJava {
 		sourceCompatibility = 11
+		options.encoding = 'UTF-8'
 	}
 
 	compileTestKotlin {
@@ -342,6 +344,22 @@ project ('spring-kafka-test') {
 	}
 }
 
+project ('spring-kafka-docs') {
+	description = 'Spring Kafka Code Snippets For Docs'
+
+	dependencies {
+		api "org.springframework.boot:spring-boot-starter:$springBootVersion"
+		api project (':spring-kafka')
+	}
+
+	compileKotlin {
+		kotlinOptions {
+			jvmTarget = '1.8'
+		}
+	}
+
+}
+
 sonarqube {
 	properties {
 		property 'sonar.links.homepage', linkHomepage
@@ -365,13 +383,14 @@ task prepareAsciidocBuild(type: Sync) {
 	from {
 		configurations.docs.collect { zipTree(it) }
 	}
-	from 'src/reference/asciidoc/'
+	from 'spring-kafka-docs/src/main/asciidoc/','spring-kafka-docs/src/main/java','spring-kafka-docs/src/main/kotlin'
 	into "$buildDir/asciidoc"
 }
 
 asciidoctorPdf {
 	dependsOn prepareAsciidocBuild
 	baseDirFollowsSourceFile()
+	configurations 'asciidoctorExt'
 
 	asciidoctorj {
 		sourceDir "$buildDir/asciidoc"
@@ -390,9 +409,34 @@ asciidoctorPdf {
 	}
 }
 
+asciidoctorj {
+	version = '2.4.1'
+	// fatalWarnings ".*"
+	options doctype: 'book', eruby: 'erubis'
+	attributes([
+			icons: 'font',
+			idprefix: '',
+			idseparator: '-',
+			docinfo: 'shared',
+			revnumber: project.version,
+			sectanchors: '',
+			sectnums: '',
+			'source-highlighter': 'highlight.js',
+			highlightjsdir: 'js/highlight',
+			'highlightjs-theme': 'googlecode',
+			stylesdir: 'css/',
+			stylesheet: 'stylesheet.css',
+			'spring-version': project.version,
+			'project-version': project.version,
+			'java-examples': 'org/springframework/kafka/jdocs',
+			'kotlin-examples': 'org/springframework/kafka/kdocs'
+	])
+}
+
 asciidoctor {
 	dependsOn asciidoctorPdf
 	baseDirFollowsSourceFile()
+	configurations 'asciidoctorExt'
 	sourceDir = file("$buildDir/asciidoc")
 	sources {
 		include '*.adoc'
@@ -402,25 +446,7 @@ asciidoctor {
 			include 'images/*', 'css/**', 'js/**'
 		}
 	}
-	options doctype: 'book', eruby: 'erubis'
 
-	attributes 'docinfo': 'shared',
-		stylesdir: "css/",
-		stylesheet: 'spring.css',
-		'linkcss': true,
-		'icons': 'font',
-		'sectanchors': '',
-		'source-highlighter': 'highlight.js',
-		'highlightjsdir': 'js/highlight',
-		'highlightjs-theme': 'github',
-		'idprefix': '',
-		'idseparator': '-',
-		'spring-version': project.version,
-		'allow-uri-read': '',
-		'toc': 'left',
-		'toclevbels': '4',
-		revnumber: project.version,
-		'project-version': project.version
 }
 
 task reference(dependsOn: asciidoctor) {
@@ -522,3 +548,5 @@ publishing {
 		}
 	}
 }
+
+apply from: "${rootDir}/gradle/docs.gradle"

gradle/docs.gradle

@@ -0,0 +1,16 @@
+configurations {
+	asciidoctorExt
+}
+
+dependencies {
+	asciidoctorExt("io.spring.asciidoctor:spring-asciidoctor-extensions-block-switch:0.5.0")
+}
+
+repositories {
+	maven {
+		url "https://repo.spring.io/release"
+		mavenContent {
+			includeGroup "io.spring.asciidoctor"
+		}
+	}
+}

settings.gradle

@@ -20,3 +20,4 @@ rootProject.name = 'spring-kafka-dist'
 
 include 'spring-kafka'
 include 'spring-kafka-test'
+include 'spring-kafka-docs'

spring-kafka-docs/build.gradle

@@ -0,0 +1,21 @@
+jar {
+    enabled = false
+}
+
+sourcesJar {
+    enabled = false
+}
+
+javadocJar {
+    enabled = false
+}
+
+publishMavenJavaPublicationToMavenLocal {
+    enabled = false
+}
+
+project.afterEvaluate {
+
+    project.tasks.artifactoryPublish.enabled(false)
+
+}

src/reference/asciidoc/appendix.adoc → spring-kafka-docs/src/main/asciidoc/appendix.adoc

@@ -7,10 +7,9 @@ This is especially true when using the embedded Kafka broker in `spring-kafka-te
 
 IMPORTANT: Backwards compatibility is not supported for all Boot versions; Spring for Apache Kafka 2.6 has been tested with Spring Boot 2.4 and 2.3.
 
-**maven**
-
 ====
-[source, xml, subs="+attributes"]
+[source, xml, subs="+attributes", role="primary"]
+.Maven
 ----
 <dependency>
     <groupId>org.springframework.kafka</groupId>
@@ -61,12 +60,9 @@ IMPORTANT: Backwards compatibility is not supported for all Boot versions; Sprin
     <scope>test</scope>
 </dependency>
 ----
-====
 
-**gradle**
-
-====
-[source, groovy, subs="+attributes"]
+[source, groovy, subs="+attributes", role="secondary"]
+.Gradle
 ----
 dependencies {
 

spring-kafka-docs/src/main/asciidoc/css/stylesheet.css

@@ -0,0 +1,31 @@
+@import 'css/spring.css';
+
+.listingblock .switch {
+    border-style: none;
+    display: inline-block;
+    position: relative;
+    bottom: -3px;
+}
+
+.listingblock .switch--item {
+    padding: 10px;
+    background-color: #e6e1dc;
+    color: #282c34;
+    display: inline-block;
+    cursor: pointer;
+    border-top-left-radius: 4px;
+    border-top-right-radius: 4px;
+}
+
+.listingblock .switch--item:not(:first-child) {
+    border-style: none;
+}
+
+.listingblock .switch--item.selected {
+    background-color: #282c34;
+    color: #e6e1dc;
+}
+
+.listingblock pre.highlightjs {
+    padding: 0;
+}

src/reference/asciidoc/index.adoc → spring-kafka-docs/src/main/asciidoc/index.adoc

@@ -11,7 +11,7 @@ ifdef::backend-html5[]
 *{project-version}*
 endif::[]
 
-(C) 2016 - 2020 by Pivotal Software, Inc.
+(C) 2016 - 2021 VMware, Inc.
 
 Copies of this document may be made for your own use and for distribution to others, provided that you do not charge any fee for such copies and further provided that each copy contains this Copyright Notice, whether distributed in print or electronically.
 

src/reference/asciidoc/kafka.adoc → spring-kafka-docs/src/main/asciidoc/kafka.adoc

@@ -77,70 +77,31 @@ Version 2.3 introduced a new class `TopicBuilder` to make creation of such beans
 The following example shows how to do so:
 
 ====
-[source, java]
+[source, java, indent=0, role="primary"]
+.Java
 ----
-@Bean
-public KafkaAdmin admin() {
-    Map<String, Object> configs = new HashMap<>();
-    configs.put(AdminClientConfig.BOOTSTRAP_SERVERS_CONFIG, ...);
-    return new KafkaAdmin(configs);
-}
-
-@Bean
-public NewTopic topic1() {
-    return TopicBuilder.name("thing1")
-            .partitions(10)
-            .replicas(3)
-            .compact()
-            .build();
-}
-
-@Bean
-public NewTopic topic2() {
-    return TopicBuilder.name("thing2")
-            .partitions(10)
-            .replicas(3)
-            .config(TopicConfig.COMPRESSION_TYPE_CONFIG, "zstd")
-            .build();
-}
-
-@Bean
-public NewTopic topic3() {
-    return TopicBuilder.name("thing3")
-            .assignReplicas(0, Arrays.asList(0, 1))
-            .assignReplicas(1, Arrays.asList(1, 2))
-            .assignReplicas(2, Arrays.asList(2, 0))
-            .config(TopicConfig.COMPRESSION_TYPE_CONFIG, "zstd")
-            .build();
-}
+include::{java-examples}/topics/Config.java[tag=topicBeans]
+----
+[source, kotlin, indent=0, role="secondary"]
+.Kotlin
+----
+include::{kotlin-examples}/topics/Config.kt[tag=topicBeans]
 ----
 ====
 
 Starting with version 2.6, you can omit `.partitions()` and/or `replicas()` and the broker defaults will be applied to those properties.
 The broker version must be at least 2.4.0 to support this feature - see https://cwiki.apache.org/confluence/display/KAFKA/KIP-464%3A+Defaults+for+AdminClient%23createTopic[KIP-464].
 
 ====
-[source, java]
+[source, java, indent=0, role="primary"]
+.Java
 ----
-@Bean
-public NewTopic topic4() {
-    return TopicBuilder.name("defaultBoth")
-            .build();
-}
-
-@Bean
-public NewTopic topic5() {
-    return TopicBuilder.name("defaultPart")
-            .replicas(1)
-            .build();
-}
-
-@Bean
-public NewTopic topic6() {
-    return TopicBuilder.name("defaultRepl")
-            .partitions(3)
-            .build();
-}
+include::{java-examples}/topics/Config.java[tag=brokerProps]
+----
+[source, kotlin, indent=0, role="secondary"]
+.Kotlin
+----
+include::{kotlin-examples}/topics/Config.kt[tag=brokerProps]
 ----
 ====