Kotlin 2.0.20 begins a change to the data class copy function. Currently, when you create a data class using a private constructor, the automatically generated .copy() function doesn’t provide the same visibility. In future Kotlin releases, the default visibility of the .copy() function will be the same as the constructor. Kotlin 2.2.20 starts this migration plan by issuing warnings in code where the visibility will change in the future.
Additionally, Kotlin 2.0.20 adds support for Gradle versions 8.6 to 8.8, and introduces a new option for sharing JVM artifacts between Gradle projects as class files.
For Kotlin Multiplatform development, Kotlin 2.0.20 offers improvements to source set management in multiplatform projects along with deprecation of compatibility with some Gradle plugins due to recent changes in Gradle.