I should share my excitement here.
We finally did it.
After 7 years, 8 months, and 12 days after first adding Kotlin to the project, we have 100% Kotlin project K kodee happy
There are no other languages in the project (excluding gradlew and gradlew.bat scripts and 1 more shell script)
It was a long but pretty smooth road of migration, and most of this time, it was just the "do not touch old code" phase.