All-open compiler plugin

Add the plugin in your build.gradle(.kts) file:

plugins {
    kotlin("plugin.allopen") version "2.1.20"
}

plugins {
    id "org.jetbrains.kotlin.plugin.allopen" version "2.1.20"
}

Then specify the list of annotations that will make classes open:

allOpen {
    annotation("com.my.Annotation")
    // annotations("com.another.Annotation", "com.third.Annotation")
}

allOpen {
    annotation("com.my.Annotation")
    // annotations("com.another.Annotation", "com.third.Annotation")
}

If the class (or any of its superclasses) is annotated with com.my.Annotation, the class itself and all its members will become open.

It also works with meta-annotations:

@com.my.Annotation
annotation class MyFrameworkAnnotation

@MyFrameworkAnnotation
class MyClass // will be all-open

MyFrameworkAnnotation is annotated with the all-open meta-annotation com.my.Annotation, so it becomes an all-open annotation as well.

Add the plugin in your pom.xml file:

<plugin>
    <artifactId>kotlin-maven-plugin</artifactId>
    <groupId>org.jetbrains.kotlin</groupId>
    <version>${kotlin.version}</version>

    <configuration>
        <compilerPlugins>
            <!-- Or "spring" for the Spring support -->
            <plugin>all-open</plugin>
        </compilerPlugins>

        <pluginOptions>
            <!-- Each annotation is placed on its own line -->
            <option>all-open:annotation=com.my.Annotation</option>
            <option>all-open:annotation=com.their.AnotherAnnotation</option>
        </pluginOptions>
    </configuration>

    <dependencies>
        <dependency>
            <groupId>org.jetbrains.kotlin</groupId>
            <artifactId>kotlin-maven-allopen</artifactId>
            <version>${kotlin.version}</version>
        </dependency>
    </dependencies>
</plugin>

Please refer to the Gradle section for the detailed information about how all-open annotations work.

If you use Spring, you can enable the kotlin-spring compiler plugin instead of specifying Spring annotations manually. The kotlin-spring is a wrapper on top of all-open, and it behaves exactly the same way.

Add the spring plugin in your build.gradle(.kts) file:

plugins {
    id("org.jetbrains.kotlin.plugin.spring") version "2.1.20"
}

plugins {
    id "org.jetbrains.kotlin.plugin.spring" version "2.1.20"
}

In Maven, the spring plugin is provided by the kotlin-maven-allopen plugin dependency, so to enable it in your pom.xml file:

<compilerPlugins>
    <plugin>spring</plugin>
</compilerPlugins>

<dependencies>
    <dependency>
        <groupId>org.jetbrains.kotlin</groupId>
        <artifactId>kotlin-maven-allopen</artifactId>
        <version>${kotlin.version}</version>
    </dependency>
</dependencies>

The plugin specifies the following annotations:

• @Component

• @Async

• @Transactional

• @Cacheable

• @SpringBootTest

Thanks to meta-annotations support, classes annotated with @Configuration, @Controller, @RestController, @Service or @Repository are automatically opened since these annotations are meta-annotated with @Component.

Of course, you can use both kotlin-allopen and kotlin-spring in the same project.

note

If you generate the project template by the start.spring.io service, the kotlin-spring plugin will be enabled by default.

All-open compiler plugin JAR is available in the binary distribution of the Kotlin compiler. You can attach the plugin by providing the path to its JAR file using the -Xplugin kotlinc option:

-Xplugin=$KOTLIN_HOME/lib/allopen-compiler-plugin.jar

You can specify all-open annotations directly, using the annotation plugin option, or enable the preset:

# The plugin option format is: "-P plugin:<plugin id>:<key>=<value>".
# Options can be repeated.

-P plugin:org.jetbrains.kotlin.allopen:annotation=com.my.Annotation
-P plugin:org.jetbrains.kotlin.allopen:preset=spring

Presets that available for the all-open plugin are: spring, micronaut, and quarkus.