This discussion is a kind of auto-promotion 
. You’ll find the links of past talks.
Human Talks - Geneva [FR]
Our first talk about Kotlin, in 2013, with a live demo of a Kotlin Spring application.
At that time, annotation didn’t have ‘@’. 
MiXit - Lyon [FR]
2016 - Atelier utiliser Kotlin dans une architecture standard
2018 - Développez votre application multiplateforme en kotlin
2018 - Designer/codeur, comment le métier et les outils du designer graphique évoluent
KotlinConf
2017 Kotlin from the trenches
Really bad talk 
Live code with git branch switching, too complicated, at the end I’m so tired that I can hardly pronounce a phrase.
2018 Porting D3.js to Kotlin multiplatform
KNight Kyiv 2018: Multiplatform development with Kotlin