docs: public static boolean isDefaultJDKValid(Node n) {
          try {
              TaskListener listener = new StreamTaskListener(new NullStream());
              Launcher launcher = n.createLauncher(listener);
              return launcher.launch().cmds("java","-fullversion").stdout(listener).join()==0;
          } catch (IOException | InterruptedException e) {
              return false;
          }
      }