A modern programming language that makes developers happier.

kotlinlang

just received this suggestion in intellij after updating a kotlin plugin:

```
Package name 'my.example.app.country_select' doesn't match regex '[a-z][A-Za-z\d]*(\.[a-z][A-Za-z\d]*)*' less... (Ctrl+F1) 
Reports package names that do not follow the recommended naming conventions.
```
I'm curious where does this come from? It didn't complain earlier. 
I have googled for "java package name regexp" and "kotlin package name regexp" and didn't find anything on the subject.