testJdk10 - Runs the test suite on JDK 10 testJdk11 - Runs the test suite on JDK 11 testJdk12 - Runs the test suite on JDK 12 testJdk13 - Runs the test suite on JDK 13 testJdk14 - Runs the test suite on JDK 14 testJdk15 - Runs the test suite on JDK 15 testJdk16 - Runs the test suite on JDK 16 testJdk17 - Runs the test suite on JDK 17 testJdk8 - Runs the test suite on JDK 8 testJdk9 - Runs the test suite on JDK 9 For projects using multi-release jars, this compilation and testing setup is essential since the source sets require compiling with newer versions but testing through a lower version bound. So if adding Java versions to a CI matrix is something you've been doing, consider switching to compile with a single Java version and instead varying your test execution instead.