Apologies for having asked such simple question, I have only some experience with embedded Java...
I have added the
<dependency>
<groupId>org.eclipse.jetty</groupId>
<artifactId>jetty-slf4j-impl</artifactId>
<version>${jetty.version}</version>
</dependency>
to the pom.xml and now my WAR servlet finally works well with Jetty 10.0.6.
Does it make any sense to add "servlet" module, when I already have "deploy" module added?
I have tried with and without "--add-module=servlet" and could not see any difference.
Also, I am curious that when I compile my WAR file against Jetty 10.0.6 and then put it into webapps dir of the old Jetty 9.4.x installation on my Linux server, then it fails with:
Sep 04 10:38:28
afarber.de java[206224]: 2021-09-04 10:38:28.833:WARN:oejw.WebAppContext:main: Failed startup of context o.e.j.w.WebAppContext@3f56875e{/en,file:///tmp/jetty-127_0_0_1-8082-words-4_0_war-_en-any-14171957377492967902
/webapp/,UNAVAILABLE}{/var/www/words-4.0.war}
Sep 04 10:38:28
afarber.de java[206224]: java.lang.RuntimeException: java.lang.IllegalStateException: No Jetty ContextHandler, Jetty WebSocket SCI unavailable
Sep 04 10:38:28
afarber.de java[206224]: at org.eclipse.jetty.annotations.ServletContainerInitializersStarter.doStart(ServletContainerInitializersStarter.java:69)
Sep 04 10:38:28
afarber.de java[206224]: at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:73)
Shouldn't the WAR file have some standard APIs and thus run fine in both deployments, Jetty 10 and Jetty 9?
Best regards
Alex