Just a quick note that I followed all instructions of the CodeGym environment setup for IntelliJ, but was getting a build error on my first CodeGym project in IntelliJ. I use SDKMan! to manage JDK versions, and it seems that OpenJDK has not listed Java version 16.0.2 yet in SDKMan!. As soon as I installed Java version 16.0.2 (Zulu) through SDKMan!, IntelliJ builds the code fine. Just a note if others are using SDKMan!, as well. Probably need to ensure you're running the correct version (16.0.2), and not worry as much about the vendor.