The build is split into 2 libraries. A java library is built. This has access to all of wpilib.
A native C++ library is built. This has access to all of wpilib. This should implement the standard wpilib interfaces.
This uses gradle, and uses the same base setup as a standard GradleRIO robot project. This means you build with ./gradlew build, and can install the native toolchain with ./gradlew installRoboRIOToolchain. If you open this project in VS Code with the wpilib extension installed, you will get intellisense set up for both C++ and Java.
By default, this template builds against the latest WPILib development build. To build against the last WPILib tagged release, build with ./gradlew build -PreleaseMode.