feat: translate all the gradle plugin samples to Kotlin

also

 - refactor the tests to keep them DRY
 - use the plugins block in documentation samples
 - use a pluginsManagement block in settings for snapshot and milestone versions and gradle version >= 4.10
 - set the plugins classpath from the test rather than in each build script
 - add a section showing how to apply the dependency management plugins declaratively

Author: jnizet

spring-boot-project/spring-boot-parent/pom.xml

@@ -26,6 +26,7 @@
 		<maven.version>3.5.4</maven.version>
 		<maven-resolver.version>1.1.1</maven-resolver.version>
 		<spock.version>1.0-groovy-2.4</spock.version>
+		<dependency-management-plugin.version>1.0.6.RELEASE</dependency-management-plugin.version>
 	</properties>
 	<scm>
 		<url>http://github.com/spring-projects/spring-boot</url>
@@ -111,7 +112,7 @@
 			<dependency>
 				<groupId>io.spring.gradle</groupId>
 				<artifactId>dependency-management-plugin</artifactId>
-				<version>1.0.6.RELEASE</version>
+				<version>${dependency-management-plugin.version}</version>
 			</dependency>
 			<dependency>
 				<groupId>jline</groupId>

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/pom.xml

@@ -127,6 +127,13 @@
 			</plugin>
 		</plugins>
 	</build>
+	<pluginRepositories>
+		<pluginRepository>
+			<id>springio</id>
+			<name>Spring IO releases repository</name>
+			<url>https://repo.spring.io/release</url>
+		</pluginRepository>
+	</pluginRepositories>
 	<profiles>
 		<profile>
 			<id>windows</id>
@@ -274,6 +281,7 @@
 								<github-tag>${github-tag}</github-tag>
 								<version-type>${version-type}</version-type>
 								<version>${project.version}</version>
+								<dependency-management-plugin-version>${dependency-management-plugin.version}</dependency-management-plugin-version>
 							</attributes>
 						</configuration>
 						<dependencies>
@@ -282,6 +290,11 @@
 								<artifactId>asciidoctorj-pdf</artifactId>
 								<version>1.5.0-alpha.11</version>
 							</dependency>
+							<dependency>
+								<groupId>io.spring.asciidoctor</groupId>
+								<artifactId>spring-asciidoctor-extensions</artifactId>
+								<version>0.1.3.RELEASE</version>
+							</dependency>
 						</dependencies>
 					</plugin>
 					<plugin>

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/asciidoc/getting-started.adoc

@@ -6,22 +6,91 @@ To get started with the plugin it needs to be applied to your project.
 ifeval::["{version-type}" == "RELEASE"]
 The plugin is https://plugins.gradle.org/plugin/org.springframework.boot[published to
 Gradle's plugin portal] and can be applied using the `plugins` block:
-[source,groovy,indent=0,subs="verbatim,attributes"]
+[source,groovy,indent=0,subs="verbatim,attributes",role="primary"]
+.Groovy
 ----
 include::../gradle/getting-started/apply-plugin-release.gradle[]
 ----
+
+[source,kotlin,indent=0,subs="verbatim,attributes",role="secondary"]
+.Kotlin
+----
+include::../gradle/getting-started/apply-plugin-release.gradle.kts[]
+----
 endif::[]
 ifeval::["{version-type}" == "MILESTONE"]
+The plugin is published to the Spring milestones repository.
+
+For Gradle versions less than 4.10, you must apply the plugin imperatively:
+
 [source,groovy,indent=0,subs="verbatim,attributes"]
 ----
 include::../gradle/getting-started/apply-plugin-milestone.gradle[]
 ----
+
+For Gradle 4.10 and above, it can be applied using the `plugins` block:
+[source,groovy,indent=0,subs="verbatim,attributes",role="primary"]
+.Groovy
+----
+include::../gradle/getting-started/apply-plugin-release.gradle[]
+----
+
+[source,kotlin,indent=0,subs="verbatim,attributes",role="secondary"]
+.Kotlin
+----
+include::../gradle/getting-started/apply-plugin-release.gradle.kts[]
+----
+
+provided you add the following lines in the `settings.gradle` file (or `settings.gradle.kts` in Kotlin):
+
+[source,groovy,indent=0,subs="verbatim,attributes",role="primary"]
+.Groovy
+----
+include::../gradle/getting-started/milestone-settings.gradle[]
+----
+
+[source,kotlin,indent=0,subs="verbatim,attributes",role="secondary"]
+.Kotlin
+----
+include::../gradle/getting-started/milestone-settings.gradle.kts[]
+----
 endif::[]
 ifeval::["{version-type}" == "SNAPSHOT"]
+The plugin is published to the Spring snapshots repository.
+
+For Gradle versions less than 4.10, you must apply the plugin imperatively:
+
 [source,groovy,indent=0,subs="verbatim,attributes"]
 ----
 include::../gradle/getting-started/apply-plugin-snapshot.gradle[]
 ----
+
+For Gradle 4.10 and above, it can be applied using the `plugins` block:
+[source,groovy,indent=0,subs="verbatim,attributes",role="primary"]
+.Groovy
+----
+include::../gradle/getting-started/apply-plugin-release.gradle[]
+----
+
+[source,kotlin,indent=0,subs="verbatim,attributes",role="secondary"]
+.Kotlin
+----
+include::../gradle/getting-started/apply-plugin-release.gradle.kts[]
+----
+
+provided you add the following lines in the `settings.gradle` file (or `settings.gradle.kts` in Kotlin):
+
+[source,groovy,indent=0,subs="verbatim,attributes",role="primary"]
+.Groovy
+----
+include::../gradle/getting-started/snapshot-settings.gradle[]
+----
+
+[source,kotlin,indent=0,subs="verbatim,attributes",role="secondary"]
+.Kotlin
+----
+include::../gradle/getting-started/snapshot-settings.gradle.kts[]
+----
 endif::[]
 
 Applied in isolation the plugin makes few changes to a project. Instead, the plugin
@@ -34,10 +103,18 @@ A typical Spring Boot project will apply the {groovy-plugin}[`groovy`],
 plugin and the {dependency-management-plugin}[`io.spring.dependency-management`] plugin as
 a minimum. For example:
 
-[source,groovy,indent=0,subs="verbatim,attributes"]
+
+[source,groovy,indent=0,subs="verbatim,attributes",role="primary"]
+.Groovy
 ----
 include::../gradle/getting-started/typical-plugins.gradle[tags=apply]
 ----
 
+[source,kotlin,indent=0,subs="verbatim,attributes",role="secondary"]
+.Kotlin
+----
+include::../gradle/getting-started/typical-plugins.gradle.kts[tags=apply]
+----
+
 To learn more about how the Spring Boot plugin behaves when other plugins are applied
 please see the section on <<reacting-to-other-plugins, reacting to other plugins>>.

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/asciidoc/index.adoc

@@ -37,7 +37,8 @@ Andy Wilkinson
 The Spring Boot Gradle Plugin provides Spring Boot support in https://gradle.org[Gradle],
 allowing you to package executable jar or war archives, run Spring Boot applications, and
 use the dependency management provided by `spring-boot-dependencies`. Spring Boot's
-Gradle plugin requires Gradle 4.4 or later.
+Gradle plugin requires Gradle 4.4 or later. If you choose to use the newer Kotlin DSL,
+it requires Gradle 4.10 or later.
 
 In addition to this user guide, {api-documentation}[API documentation] is also available.
 
@@ -47,4 +48,4 @@ include::packaging.adoc[]
 include::publishing.adoc[]
 include::running.adoc[]
 include::integrating-with-actuator.adoc[]
-include::reacting.adoc[]
+include::reacting.adoc[]

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/asciidoc/integrating-with-actuator.adoc

@@ -10,11 +10,19 @@ build in the presence of a `META-INF/build-info.properties` file. A
 {build-info-javadoc}[`BuildInfo`] task is provided to generate this file. The easiest way
 to use the task is via the plugin's DSL:
 
-[source,groovy,indent=0,subs="verbatim"]
+[source,groovy,indent=0,subs="verbatim,attributes",role="primary"]
+.Groovy
 ----
 include::../gradle/integrating-with-actuator/build-info-basic.gradle[tags=build-info]
 ----
 
+[source,kotlin,indent=0,subs="verbatim,attributes",role="secondary"]
+.Kotlin
+----
+include::../gradle/integrating-with-actuator/build-info-basic.gradle.kts[tags=build-info]
+----
+
+
 This will configure a {build-info-javadoc}[`BuildInfo`] task named `bootBuildInfo` and, if
 it exists, make the Java plugin's `classes` task depend upon it. The task's destination
 directory will be `META-INF` in the output directory of the main source set's resources
@@ -45,11 +53,19 @@ By default, the generated build information is derived from the project:
 
 The properties can be customized using the DSL:
 
-[source,groovy,indent=0,subs="verbatim"]
+[source,groovy,indent=0,subs="verbatim,attributes",role="primary"]
+.Groovy
 ----
 include::../gradle/integrating-with-actuator/build-info-custom-values.gradle[tags=custom-values]
 ----
 
+[source,kotlin,indent=0,subs="verbatim,attributes",role="secondary"]
+.Kotlin
+----
+include::../gradle/integrating-with-actuator/build-info-custom-values.gradle.kts[tags=custom-values]
+----
+
+
 The default value for `build.time` is the instant at which the project is being built. A
 side-effect of this is that the task will never be up-to-date. As a result, builds will
 take longer as more tasks, including the project's tests, will have to be executed.
@@ -59,7 +75,15 @@ than the accuracy of the `build.time` property, set `time` to `null` or a fixed
 
 Additional properties can also be added to the build information:
 
-[source,groovy,indent=0,subs="verbatim"]
+[source,groovy,indent=0,subs="verbatim,attributes",role="primary"]
+.Groovy
 ----
 include::../gradle/integrating-with-actuator/build-info-additional.gradle[tags=additional]
 ----
+
+[source,kotlin,indent=0,subs="verbatim,attributes",role="secondary"]
+.Kotlin
+----
+include::../gradle/integrating-with-actuator/build-info-additional.gradle.kts[tags=additional]
+----
+

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/asciidoc/managing-dependencies.adoc

@@ -10,11 +10,17 @@ Maven users. For example, it allows you to omit version numbers when declaring
 dependencies that are managed in the bom. To make use of this functionality, simply
 declare dependencies in the usual way but omit the version number:
 
-[source,groovy,indent=0,subs="verbatim"]
+[source,groovy,indent=0,subs="verbatim",role="primary"]
+.Groovy
 ----
 include::../gradle/managing-dependencies/dependencies.gradle[tags=dependencies]
 ----
 
+[source,kotlin,indent=0,subs="verbatim",role="secondary"]
+.Kotlin
+----
+include::../gradle/managing-dependencies/dependencies.gradle.kts[tags=dependencies]
+----
 
 
 [[managing-dependencies-customizing]]
@@ -28,11 +34,19 @@ for a complete list of these properties.
 To customize a managed version you set its corresponding property. For example, to
 customize the version of SLF4J which is controlled by the `slf4j.version` property:
 
-[source,groovy,indent=0,subs="verbatim"]
+[source,groovy,indent=0,subs="verbatim",role="primary"]
+.Groovy
 ----
 include::../gradle/managing-dependencies/custom-version.gradle[tags=custom-version]
 ----
 
+[source,kotlin,indent=0,subs="verbatim",role="secondary"]
+.Kotlin
+----
+include::../gradle/managing-dependencies/custom-version.gradle.kts[tags=custom-version]
+----
+
+
 WARNING: Each Spring Boot release is designed and tested against a specific set of
 third-party dependencies. Overriding versions may cause compatibility issues and should
 be done with care.
@@ -50,21 +64,41 @@ artifact ID, or version.
 First, configure the project to depend on the Spring Boot plugin but do not apply it:
 
 ifeval::["{version-type}" == "RELEASE"]
+[source,groovy,indent=0,subs="verbatim,attributes",role="primary"]
+.Groovy
 ----
 include::../gradle/managing-dependencies/depend-on-plugin-release.gradle[]
 ----
+
+[source,kotlin,indent=0,subs="verbatim,attributes",role="secondary"]
+.Kotlin
+----
+include::../gradle/managing-dependencies/depend-on-plugin-release.gradle.kts[]
+----
 endif::[]
 ifeval::["{version-type}" == "MILESTONE"]
-[source,groovy,indent=0,subs="verbatim,attributes"]
+[source,groovy,indent=0,subs="verbatim,attributes",role="primary"]
+.Groovy
 ----
 include::../gradle/managing-dependencies/depend-on-plugin-milestone.gradle[]
 ----
+[source,kotlin,indent=0,subs="verbatim,attributes",role="secondary"]
+.Kotlin
+----
+include::../gradle/managing-dependencies/depend-on-plugin-release.gradle.kts[]
+----
 endif::[]
 ifeval::["{version-type}" == "SNAPSHOT"]
-[source,groovy,indent=0,subs="verbatim,attributes"]
+[source,groovy,indent=0,subs="verbatim,attributes",role="primary"]
+.Groovy
 ----
 include::../gradle/managing-dependencies/depend-on-plugin-snapshot.gradle[]
 ----
+[source,kotlin,indent=0,subs="verbatim,attributes",role="secondary"]
+.Kotlin
+----
+include::../gradle/managing-dependencies/depend-on-plugin-release.gradle.kts[]
+----
 endif::[]
 
 The Spring Boot plugin's dependency on the dependency management plugin means that you
@@ -74,11 +108,31 @@ management plugin as Spring Boot uses.
 
 Apply the dependency management plugin and then configure it to import Spring Boot's bom:
 
-[source,groovy,indent=0,subs="verbatim,attributes"]
+[source,groovy,indent=0,subs="verbatim,attributes",role="primary"]
+.Groovy
 ----
 include::../gradle/managing-dependencies/configure-bom.gradle[tags=configure-bom]
 ----
 
+[source,kotlin,indent=0,subs="verbatim,attributes",role="secondary"]
+.Kotlin
+----
+include::../gradle/managing-dependencies/configure-bom.gradle.kts[tags=configure-bom]
+----
+
+
+The Kotlin code above is a bit awkward. That's because we're using the imperative way of applying
+the dependency management plugin.
+
+We can make the code less awkward by applying the plugin from
+the root parent project, or by using the `plugins` block as we're doing for the spring boot plugin.
+The downside of this method, though, is that it forces us to specify the version of the
+dependency management plugin, even though it's a dependency of the spring boot plugin:
+
+[source,kotlin,indent=0,subs="verbatim,attributes"]
+----
+include::../gradle/managing-dependencies/configure-bom-with-plugins.gradle.kts[tags=configure-bom]
+----
 
 
 [[managing-dependencies-learning-more]]