Valhalla Stage 2 - Nullness Emotion

The first stage of Valhalla (https://openjdk.org/projects/valhalla/) is almost ready, soon we will release the first stage of the rocket, the ability to declare a class as a value class. A value class object is like a cheap box that is able to solarise itself on stack, avoiding the traditional boxing cost. The next phase is to allow to flatten value class into fields, but for that we need to get ride of null as a possible value. This talk is about the challenges to introduce nullness emotion ('?' Or '!') to the Java type system. Sadly, if you hope that Java can be turned into Kotlin, you will be disappointed.