This is how to open multiple gradle projects in a single IntelliJ window.
- File -> New -> Project ... -> Empty Project
- File -> Project Structure ... -> Modules -> Plus Sign -> Import Module
- Choose your Module -> Import module from external model -> Gradle -> Next
- Activate Checkbox: "Create separate module per source set"
- Activate Radio: "Use gradle wrapper task configuration"
- Finish
- Repeat step two for every project
The steps don't seem to lead to a multi module project. I must be missing something.