Merge pull request #18573 from sdeleuze

* gh-18573:
  Polish "Update Kotlin-related reference documentation"
  Update Kotlin-related reference documentation

Closes gh-18573

spring-boot-project/spring-boot-docs/src/main/asciidoc/spring-boot-features.adoc

@@ -7614,35 +7614,40 @@ In order to avoid mixing different versions of Kotlin dependencies on the classp
 With Maven, the Kotlin version can be customized via the `kotlin.version` property and plugin management is provided for `kotlin-maven-plugin`.
 With Gradle, the Spring Boot plugin automatically aligns the `kotlin.version` with the version of the Kotlin plugin.
 
+Spring Boot also manages the version of Coroutines dependencies by importing the Kotlin Coroutines BOM.
+The version can be customized via the `kotlin-coroutines.version` property.
+
+TIP: `org.jetbrains.kotlinx:kotlinx-coroutines-reactor` dependency is provided by default if one bootstraps a Kotlin project with at least one reactive dependency on https://start.spring.io/#!language=kotlin[start.spring.io].
 
 
 [[boot-features-kotlin-configuration-properties]]
 === `@ConfigurationProperties`
-`@ConfigurationProperties` supports classes with immutable `val` properties as shown in the following example:
+`@ConfigurationProperties` when used in combination with <<boot-features-external-config-constructor-binding,`@ConstructorBinding`>> supports classes with immutable `val` properties as shown in the following example:
 
 [source,kotlin,indent=0]
 ----
+@ConstructorBinding
 @ConfigurationProperties("example.kotlin")
 data class KotlinExampleProperties(
 		val name: String,
 		val description: String,
-		val myService: MyService
-)
+		val myService: MyService) {
 
-data class MyService(
-	val apiToken: String,
-	val uri: URI
-)
+	data class MyService(
+			val apiToken: String,
+			val uri: URI
+	)
+}
 ----
 
 TIP: To generate <<appendix-configuration-metadata.adoc#configuration-metadata-annotation-processor,your own metadata>> using the annotation processor, {kotlin-docs}kapt.html[`kapt` should be configured] with the `spring-boot-configuration-processor` dependency.
-Note that some features (such as detecting the default value or deperecated items) are not working due to limitations in the model kapt provides.
+Note that some features (such as detecting the default value or deprecated items) are not working due to limitations in the model kapt provides.
 
 
 
 [[boot-features-kotlin-testing]]
 === Testing
-While it is possible to use JUnit 4 to test Kotlin code, JUnit 5 is recommended.
+While it is possible to use JUnit 4 to test Kotlin code, JUnit 5 is provided by default and is recommended.
 JUnit 5 enables a test class to be instantiated once and reused for all of the class's tests.
 This makes it possible to use `@BeforeClass` and `@AfterClass` annotations on non-static methods, which is a good fit for Kotlin.
 
@@ -7683,6 +7688,7 @@ If you need the `Mockk` equivalent of the Mockito specific <<boot-features-testi
 * https://github.com/sdeleuze/spring-kotlin-fullstack[spring-kotlin-fullstack]: WebFlux Kotlin fullstack example with Kotlin2js for frontend instead of JavaScript or TypeScript
 * https://github.com/spring-petclinic/spring-petclinic-kotlin[spring-petclinic-kotlin]: Kotlin version of the Spring PetClinic Sample Application
 * https://github.com/sdeleuze/spring-kotlin-deepdive[spring-kotlin-deepdive]: a step by step migration for Boot 1.0 + Java to Boot 2.0 + Kotlin
+* https://github.com/sdeleuze/spring-boot-coroutines-demo[spring-boot-coroutines-demo]: Coroutines sample project