Want to contribute? Great! Follow these rules.

currently we are migration codebase to kotlin, so if you are adding a new file it should be written in kotlin!

java-related rules:

This project follows Google Java Style Guide.
You can download a formatter for Intellij here.
NOTE: there might be a problem with imports order - static imports have to before other imports. You can change it in the IntelliJ settings.
io.vavr provides great collection / control types - use them!
null is bad, if something may be nullable / may not exist use io.vavr.control.Option.
use io.vavr.collection.List instead of java.util.List - it allows using .map without .stream()...

general rules:

try to avoid throwing exceptions - use io.vavr.control.Try.
remember to use buildifier.
The usage: buildifier -r .
remember to update the changelog.
tests tests tests - write tests!