run-forked Does Not Start Jetty Server - maven

Question

I added a jetty-maven-plugin to my build like this:
<plugin>
<groupId>org.mortbay.jetty</groupId>
<artifactId>jetty-maven-plugin</artifactId>
<version>8.1.16.v20140903</version>
<executions>
<execution>
<id>run-jetty</id>
<goals>
<goal>run</goal>
</goals>
<phase>install</phase>
<configuration>
<webAppSourceDirectory>${basedir}/target/repository/</webAppSourceDirectory>
<webApp>
<contextPath>/site</contextPath>
</webApp>
<!-- run only -->
<scanIntervalSeconds>10</scanIntervalSeconds>
<!-- run-forked only -->
<stopPort>9099</stopPort>
<stopKey>stopPlease</stopKey>
<stopWait>10</stopWait>
<waitForChild>false</waitForChild>
</configuration>
</execution>
</executions>
</plugin>
When I run the surrounding Maven project, the Jetty server starts fine and I can browse the webapp at http://localhost:8080/site/
However when I replace the goal run with run-forked I get the following info in the console:
[INFO] --- jetty-maven-plugin:8.1.5.v20120716:run-forked (run-jetty) # project ---
[INFO] Configuring Jetty for project: maven-p2
[INFO] Forked process started
However nothing gets startet at http://localhost:8080/site/. At least there is no webapp there. The OS reports a Java process on port 8080 (two actually) and something listening on 9099 (I guess the stop handler).
I can't seem to figure out how to get run-forked to work as run (just in another JVM). I checked the manual for configuration I'm missing, but couldn't find anything.
mvn jetty:stop works, too and does not print "Jetty not running!", so there is a Jetty somewhere. Just no webapp.
How do I get run-forked to start my webapp?

Answer 1

Updating the Maven plug-in worked, so I guess it's a bug:
<plugin>
<groupId>org.eclipse.jetty</groupId>
<artifactId>jetty-maven-plugin</artifactId>
<version>9.4.25.v20191220</version>
<configuration>
<supportedPackagings>jar</supportedPackagings>
</configuration>
<!-- Rest of config same as above -->
</plugin>
(Note: I needed to add supportedPackagings additionally to the existing configuration else I got "packaging type [jar] is unsupported".)