toolChain

Sets the JVM toolChain version for all projects. If this is omitted, then defaultToolChain is used.

NOTE. If any of your project's dependencies use a higher tool-chain version, then the build will fail.

If your project creates libraries used by 3rd parties, consider using a low (old) tool-chain version, which gives those 3rd parties maximum flexibility. This is why the default is low (11).