Specify the JDK(s) with which builds are performed. If none is selected, the default JDK is used (no explicit `JAVA_HOME`, and `java` command is assumed to be in `PATH`.) If multiple JDKs are selected, the configuration matrix will include all of the specified JDKs.
Selecting multiple values is typically useful when this job is running tests, and you need to run tests on multiple different versions of JDKs.
During a build, the selected JDK value for the given run is available as the "jdk" axis. See the help of "axes" below for more information about how to access the axis value.