Did I got it right that KDL uses 1.15 Java wrapper? What about newer SGI 0.0.2? Please correct me, if I am wrong, I have not much insides yet, but I have learned that recent 2.x version introduced important changes in the underlying structure of TF.

We plan to move to the TF Java API 0.2.* in the upcoming updates. This should not affect the high-level APIs though. We haven't done it yet because there are still some rough edges there.

Dear @Michal Harakal 1.15 Java API is stable and frozen, performance is comparable on GPU and CPU. I am actively participated in Java API (SIG JVM) development. It's not stable and API is not ready to produce new version. But I suppose that in Kotlin DL 0.2 or 0.3 we will present the TF 2.x as a backend. Also it's just an engine. No limitation on transfer learning with new version of Keras.