Module source is in build/generated/source/annotationProcessor

I have a gradle module which I use in a multi-module project in Intellij Ultimate 2019.3.5. This module is a dependency of the other module in the same project. When I want to open classes of this module, intellij opens themc out of the dependency-jar list of the other module (External library) rather than from the module itself. I noticed that in the project structure the source of the project is located in build/generated/source:

I tried to change (i.e. remove content root) but every after gradle-reimport it appears again.

Is this a gradle configuration problem? Any idea what is the problem and how to fix it?