Java files, duh
First and foremost, function over form and "proper" programming conventions. These are not meant for users who want nice looks, shiny user interfaces, GUIs, etc...nor is their source code written to satisfy the opinions of the convention Nazis. They are written to get the job done regardless of how ugly their interfaces are or how "incorrect" and outright ugly their code is.
If you don't like that, then you're free to browse elsewhere and save your complaints about aesthetics/conventions for someone who cares.
Otherwise, enjoy!