One more try -
I have created the file $JETTY_BASE/webapps/hello.xml with the content:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE Configure PUBLIC "-//Jetty//Configure//EN" "
http://www.eclipse.org/jetty/configure_9_0.dtd">
<Configure class="org.eclipse.jetty.webapp.WebAppContext">
<Set name="contextPath">/hello</Set>
<Set name="contextPath">/</Set>
<Set name="virtualHosts">
<Array type="java.lang.String">
<Item>
slova.de</Item>
<Item>
www.slova.de</Item>
</Array>
</Set>
<Set name="war"><SystemProperty name="jetty.base"/>/webapps/hello-world-0.1-SNAPSHOT.war</Set>
</Configure>
INFO:oejsh.ContextHandler:Scanner-0: Stopped o.e.j.w.WebAppContext@9720aef{/hello,null,UNAVAILABLE}{/hello-world-0.1-SNAPSHOT.war}
INFO:oejw.StandardDescriptorProcessor:Scanner-0: NO JSP Support for /, did not find org.eclipse.jetty.jsp.JettyJspServlet
INFO:oejsh.ContextHandler:Scanner-0: Started o.e.j.w.WebAppContext@2b82fd43{/,file:///tmp/jetty-127.0.0.1-8080-hello-world-0.1-SNAPSHOT.war-_-slova.de-2204701430203830577.dir/webapp/,AVAILABLE,
slova.de}{/hello-world-0.1-SNAPSHOT.war}