Computer builtInComputer = r.jenkins.toComputer();
         Node builtInNode = builtInComputer.getNode();
         builtInNode.getNodeProperties().add(new EnvironmentVariablesNodeProperty(new EnvironmentVariablesNodeProperty.Entry("TEST_VAR_NAME", "stable")));
         r.jenkins.save();
         builtInNode.save();

         // Can try to reload, even require repopulation of cache via Java reflection - to no avail...
         // Note that disconnect/connect seems a no-op for MasterComputer instance.
         System.out.println("[DEBUG] Restart the 'built-in' Computer connection to clear its cachedEnvironment and recognize added envvar");
         builtInComputer.setTemporarilyOffline(true, new OfflineCause.ByCLI("Restart built-in to reread envvars config"));
         builtInComputer.disconnect(new OfflineCause.ByCLI("Restart built-in to reread envvars config"));
         builtInComputer.waitUntilOffline();
         r.waitUntilNoActivity();
         builtInComputer.getChannel().close();
         Thread.sleep(3000);
         r.jenkins.reload();
         builtInComputer.setTemporarilyOffline(false, null);
         builtInComputer.connect(true);
         builtInComputer.waitUntilOnline();
         r.waitUntilNoActivity();

         // Feed it to Java reflection, to clear the internal cache...
         Field f = Computer.class.getDeclaredField("cachedEnvironment");
         f.setAccessible(true);
         f.set(builtInComputer, null);

         // Query:
         System.out.println("[DEBUG] builtIn node env: " + builtInComputer.getEnvironment());