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Document problem with property binding and Kotlin value classes

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Closes gh-41693
This commit is contained in:
Andy Wilkinson
2024-09-06 14:22:40 +01:00
parent a89ae3fbee
commit e30ae7a240
1 changed files with 5 additions and 1 deletions
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6
spring-boot-project/spring-boot-docs/src/docs/asciidoc/features/kotlin.adoc
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@@ -108,7 +108,7 @@ TIP: `org.jetbrains.kotlinx:kotlinx-coroutines-reactor` dependency is provided b
[[features.kotlin.configuration-properties]]
=== @ConfigurationProperties
`@ConfigurationProperties` when used in combination with <<features#features.external-config.typesafe-configuration-properties.constructor-binding,constructor binding>> supports classes with immutable `val` properties as shown in the following example:
`@ConfigurationProperties` when used in combination with <<features#features.external-config.typesafe-configuration-properties.constructor-binding,constructor binding>> supports data classes with immutable `val` properties as shown in the following example:
[source,kotlin,indent=0,subs="verbatim"]
----
@@ -125,6 +125,10 @@ data class KotlinExampleProperties(
}
----
Due to the limitations of their interoperability with Java, support for value classes is limited.
In particular, relying upon a value class's default value will not work with configuration property binding.
In such cases, a data class should be used instead.
TIP: To generate <<configuration-metadata#appendix.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 deprecated items) are not working due to limitations in the model kapt provides.