Has somebody managed running GWT Super Dev with GWT 2.9.0 and Java 11?

Question

I maintain a GWT project dated back to the good old golden GWT-days in 2009. Meanwhile, a whole bunch of things happened and we like to update the project as far as possible (currently Java8, GWT 2.8.2).

Fighting with my dependency-configuration I managed to setup things packaging and running with Java 11 (and language level 11) and Tomcat 9. We use the (deprecated as far as I understood) gwt-maven-plugin (2.9.0) which runs the compile phase errorless - my final output is a war-file with everything in place as expected.

But when it comes to development, hence running Super Dev Mode, the real pain begins. IntelliJ integration won't start the SuperDev target anymore. The plugin's gwt:run target the same.

The plugin references jetty 9.2.14.v20151106 jars (via gwt-dev/gwt), which are not usable with Java 9+. So I excluded those and replaced the jars with more recent versions (9.4.29.v20200521, 9.4.30.v20200611) - one step further.

To address the Java 9 game, I created a module-info.java to point out all my references, and resolved conflicts there - another step.

But now I reached a blocking-point:

Super Dev Mode starts stating:

00:00:09,427 [ERROR] Found resouce but unrecognized URL format: 'jrt:/java.scripting/javax/script/ScriptEngineManager.class'

(though I referenced java.scripting module)

My hostpage displays HTTP 503

From there, no other clues (error-out or stacktraces) are visible to me.

After spending three days on the issue so far, my frustration is starting to rise... I'm right before flipping tables.

Has somebody had success starting GWT Super Dev Mode with GWT 2.9.0 in a reasonable real-live project (JPA, Spring, ...)?

Love to share my findings if you face similar hurdles.

Best, Dan

p.s.: I tried net.ltgt.gwt.maven gwt-maven-plugin with no success, but that might be other configuration flaws.

pp.s.: In a Java 8 environment, I am able to use GWT 2.9.0 and it's Super Dev Mode (via IntelliJ and gwt-maven-plugin).