This setting controls the Java bytecode version that the Kotlin compiler emits for JVM and Android targets. The -Xjdk-release flag is useful for the Kotlin JVM plugin or the JVM targets of the Kotlin multiplatform plugin to ensure compatibility with your target minimum JVM. Users of the Kotlin Android plugin or the Android targets of the Kotlin multiplatform plugin do not need to do this, as the use of the android.jar as the boot classpath limits the java.