Why Android Studio doesn't allow me to create Java Classes?

android, android-gradle-plugin, android-studio

Solution

Right click on the src folder, Mark Directory As -> Source Root.

Problem

Starting from the update to Android Studio 2 days ago, it doesn't let me create Java classes anymore. And the current classes now have a strange symbol. I tried to export and import many times with different configuration but they never worked. Any advice? Here are two screenshots: Here is the structure of my Android Studio project. AndroidManifest is in the right place:

Original source