Just released roboquant version 1.5.0 (
https://github.com/neurallayer/roboquant). It is an algo-trading platform written in 100% Kotlin. Besides using it as a normal library, there is also the option to develop interactively in Kotlin Jupyter Notebooks. You can see some of the charts over here
https://roboquant.org/charts.html.
If you interested in trading & Kotlin, feel free to reach out!!!