The goal of Dotlin is not to make code shareable between Kotlin/JVM and Dart, but rather to bring the Kotlin language (and extra features) to the Dart runtime.

However, depending on the data classes you could still do this, if they're simple enough. You could then compile those specific files with Dotlin and you'd have some code sharing. But you might run in some trouble with stdlib definitions, for example Int, which is 64-bit in Dotlin/Dart and 32-bit in Kotlin.

Hope that helps 👍