<!--- Thank you for contributing to Magento. To help us process this issue we recommend that you add the following information: - Summary of the issue, - Expected and actual results, Fields marked with (*) are required. Please don't remove the template. --> **Is your feature request related to a problem? Please describe.** When I develop modules that will be distributed by composer, I use custom "extensions" directory than app/code. Like described here: https://www.yireo.com/blog/2019-05-10-local-composer-development-with-magento2 . **Describe the solution you'd like** (*) It would be nice, to have option to select custom module as a second code source for plugin, so all plugin features will be also available there. **Additional context** https://www.yireo.com/blog/2019-05-10-local-composer-development-with-magento2 **From Slack discussion:**  About content roots: https://www.jetbrains.com/help/idea/content-roots.html