Kotlin sample code, documentation improvements

README.md

@@ -72,7 +72,7 @@ Picocli-based applications can easily [integrate](https://picocli.info/#_depende
 The [Micronaut](https://micronaut.io/) microservices framework has [built-in support](https://docs.micronaut.io/latest/guide/index.html#commandLineApps) for picocli.
 Picocli ships with a [`picocli-spring-boot-starter` module](https://github.com/remkop/picocli/tree/master/picocli-spring-boot-starter) 
 that includes a `PicocliSpringFactory` and Spring Boot auto-configuration to use Spring dependency injection in your picocli command line application.
-The user manual has an [example](https://picocli.info/#_guice_example) of integrating with Guice.
+The user manual has examples of integrating with [Guice](https://picocli.info/#_guice_example), [Spring Boot](https://picocli.info/#_spring_boot_example), [Micronaut](https://picocli.info/#_micronaut_example), [Quarkus](https://picocli.info/#_quarkus_example) and with containers that comply to [CDI 2.0 specification](https://picocli.info/#_cdi_2_0_jsr_365) (JSR 365).
 
 ### Releases
 * [All Releases](https://github.com/remkop/picocli/releases)
@@ -106,7 +106,6 @@ The user manual has an [example](https://picocli.info/#_guice_example) of integr
 * [CLI applications with GraalVM Native Image](https://medium.com/graalvm/cli-applications-with-graalvm-native-image-d629a40aa0be) (2020-11-13) by [Oleg Šelajev](https://twitter.com/shelajev).
 * [Picocli subcommands - One program, many purposes](https://aragost.com/blog/java/picocli-subcommands.html) (2020-09-22) by [Jonas Andersen](https://twitter.com/PrimusAlgo).
 * [How to build a CLI app in Java using jbang and picocli](https://www.twilio.com/blog/cli-app-java-jbang-picocli) (2020-08-13) by [Matthew Gilliard](https://twitter.com/MaximumGilliard).
-* [VIDEO] [Tuesday Java Lunch & Learn. This week: picocli](https://m.twitch.tv/videos/706906131) (2020-08-11) by MaximumGilliard - twitch.tv.
 * [Building a GitHub Dependents Scraper with Quarkus and Picocli](https://blog.marcnuri.com/github-dependents-scraper-quarkus-picocli/) (2020-07-31) by [Marc Nuri](https://twitter.com/MarcNuri).
 * [Building a decent Java CLI](https://atextor.de/2020/07/27/building-a-decent-java-cli.html) (2020-07-27) by [Andreas Textor](https://twitter.com/atextor).
 * [VIDEO] (Another very well-produced video by Szymon Stepniak) [OAuth 2.0 in a Java command-line app | #micronaut #picocli #oauth2](https://www.youtube.com/watch?v=js5H9UbmmMY) (2020-07-23) by [Szymon Stepniak](https://e.printstacktrace.blog/) ([YouTube channel](https://www.youtube.com/channel/UCEf8e5YAYnowq-2deW4tpsw)).

docs/index.adoc

@@ -11091,7 +11091,7 @@ class MailServiceImpl : IMailService {
 <1> The `JavaMailSender` is provided by the Spring framework.
 <2> Once a mail was successful sent, a log message will be emitted.
 
-Finally we have to configure our mail service. This can be done inside a file `application properties`, which we put in a `config` subdirectory of your project:
+Finally we have to configure our mail service. This can be done inside a file `application.properties`, which we put in a `config` subdirectory of your project:
 
 .application.properties
 ----
@@ -11669,7 +11669,8 @@ Additionally, you can do white box testing by keeping a reference to the applica
 
 For example:
 
-[source,java]
+.Java
+[source,java, role=primary]
 ----
 MyApp app = new MyApp();
 CommandLine cmd = new CommandLine(app);
@@ -11687,10 +11688,30 @@ assertEquals("expectedValue1", app.getState1());
 assertEquals("expectedValue2", app.getState2());
 ----
 
+.Kotlin
+[source,kotlin,role="secondary"]
+----
+val app = MyApp()
+val cmd = CommandLine(app)
+
+val sw = StringWriter()
+cmd.out = PrintWriter(sw)
+
+// black box testing
+val exitCode = cmd.execute("-x", "-y=123")
+assertEquals(0, exitCode)
+assertEquals("Your output is abc...", sw.toString())
+
+// white box testing
+assertEquals("expectedValue1", app.state1)
+assertEquals("expectedValue2", app.state2)
+----
+
 This assumes that the application uses the `PrintWriter` provided by https://picocli.info/apidocs/picocli/CommandLine.html#getOut--[`CommandLine.getOut`] or  https://picocli.info/apidocs/picocli/CommandLine.html#getErr--[`CommandLine.getErr`].
 Applications can get these writers via the <<#spec-annotation,`@Spec`>> annotation:
 
-[source,java]
+.Java
+[source,java,role=primary]
 ----
 @Command
 class MyApp implements Runnable {
@@ -11703,8 +11724,22 @@ class MyApp implements Runnable {
 }
 ----
 
+.Kotlin
+[source,kotlin,role=secondary]
+----
+@Command
+class MyApp : Runnable {
+    @Spec lateinit var spec: CommandSpec
+
+    override fun run() {
+        // make testing easier by printing to the Err and Out streams provided by picocli
+        spec.commandLine().out.println("Your output is abc...")
+    }
+}
+----
+
 === Testing the Output
-Applications that print to `System.out` or `System.err` directly, or use a version of picocli older than 4.0, can be tested by capturing the standard output and error streams.
+Applications that print to `System.out` or `System.err` directly, or use a version of picocli lower than 4.0, can be tested by capturing the standard output and error streams.
 There are various options for doing this, some of which are shown below.
 
 ==== Java 8+ with System-Lambda

gradle.properties

@@ -13,7 +13,7 @@ jlineVersion        = 2.14.6
 jline3Version       = 3.18.0
 junitDepVersion     = 4.11
 junitVersion        = 4.12
-springBootVersion   = 2.4.1
+springBootVersion   = 2.4.3
 
 # projectPreviousReleaseVersion is non-SNAPSHOT, only published releases
 projectPreviousReleaseVersion = 4\\.6\\.1

gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-6.8.2-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.8.3-all.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists

picocli-examples/build.gradle

@@ -6,7 +6,7 @@ buildscript {
     }
 
     dependencies {
-        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.4.21"
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.4.31"
     }
 }
 
@@ -38,7 +38,7 @@ dependencies {
                    "org.hibernate.validator:hibernate-validator-annotation-processor:6.1.2.Final",
                    "javax.el:javax.el-api:3.0.0",
                    "org.glassfish.web:javax.el:2.2.6"
-    implementation "org.jetbrains.kotlin:kotlin-script-runtime:1.4.21"
+    implementation "org.jetbrains.kotlin:kotlin-script-runtime:1.4.31"
 }
 tasks.withType(GroovyCompile) {
     // this, and the `configurations {ivy}` section, are a workaround for the dreaded