Changing Routes of the application should work after compiling the class without restarting the server

[mehdi-vaadin]

When building apps, I want to be able to add new views to my app, and after compiling the (Java) code, be able to open them in the browser, without restarting the server.

Acceptance criteria

• It should work with jetty-maven-plugin
• It should work with Hotswap agent
• It should work with JRebel
• It should work with spring-dev-tools for Spring apps
• It should work with Wildfly maven plugin for CDI apps
• It should work with TomEE maven plugin for CDI apps
• Deleting a route, adding a new route and renaming a route should be supported

NOTE If initial investigation indicates that any of the servers / tools require changes to make it work, create a new ticket explicitly for this.

[joheriks]

Live reload with Wildfly Maven plugin will most likely not be doable without updates to the plugin itself: https://issues.redhat.com/browse/WFMP-71.

[joheriks]

Result of investigation

All tests by running the corresponding starter app via Maven from IntelliJ (with no additional plugins or non-default settings, except JRebel plugin which was enabled only for JRebel test).

Add: Adding a new view class with a unique @Route annotation. Test passes if the route is navigable.
Update: Change the value of the @Route annotation of an existing class, without renaming the class. Test passes if the new route is navigable, and the route with the previous name is no longer navigable.
Delete: Remove a @Route annotated class that is navigable. Test passes if route is no longer navigable after removal of the class.
Keep session: Whether the session survives the the redeploy cycle.

	Add	Update	Delete	Keep session
jetty-maven-plugin auto-scan	y	y	y	n
HotSwap agent (jetty)	y †	n ‡	n	y †
JRebel (jetty)	y	y	y	y
spring-boot-devtools	y	y	y	y
CDI (TomEE)	y	y	n	y ❊

†) Works when running Maven's jetty:run from IntelliJ, however, see issue with Hotswap Agent in general (#7174)
‡) The new route gets added, but the old one remains navigable.
❊) Serialization issue in CDI starter fixable by updating starter (see comment in vaadin/skeleton-starter-flow-cdi#137)