enable GZIP in jetty (usign maven-jetty-plugin)

Question

I can't seem to get GZIP compression working in mvn jetty:run. I added a jetty-gzip.xml

pom.xml

  ...
    <jetty9.version>9.4.18.v20190429</jetty9.version>  
  ...
        <plugin>
            <groupId>org.eclipse.jetty</groupId>
            <artifactId>jetty-maven-plugin</artifactId>
            <version>${jetty9.version}</version>
            <configuration>
                <reload>manual</reload>

                <systemProperties>
                    <systemProperty>
                        <name>maven.project.build.directory.test-classes</name>
                        <value>${project.build.directory}/test-classes</value>
                    </systemProperty>
                </systemProperties>
                <jettyXml>
                    ${project.basedir}/src/test/jetty/jetty.xml,${project.basedir}/src/test/jetty/jetty-ssl.xml,${project.basedir}/src/test/jetty/jetty-http.xml,${project.basedir}/src/test/jetty/jetty-https.xml,${project.basedir}/src/test/jetty/jetty-gzip.xml,
                </jettyXml>
            </configuration>
        </plugin>

jetty-gzip.xml

<Configure id="Server" class="org.eclipse.jetty.server.Server">
    <Call name="insertHandler">
        <Arg>
            <New id="GzipHandler" class="org.eclipse.jetty.server.handler.gzip.GzipHandler">
                <Set name="minGzipSize"><Property name="jetty.gzip.minGzipSize" deprecated="gzip.minGzipSize" default="1024"/></Set>
                <Set name="checkGzExists"><Property name="jetty.gzip.checkGzExists" deprecated="gzip.checkGzExists" default="false"/></Set>
                <Set name="compressionLevel"><Property name="jetty.gzip.compressionLevel" deprecated="gzip.compressionLevel" default="-1"/></Set>
                <Set name="inflateBufferSize"><Property name="jetty.gzip.inflateBufferSize" default="0"/></Set>
                <Set name="deflaterPoolCapacity"><Property name="jetty.gzip.deflaterPoolCapacity" default="-1"/></Set>
                <Set name="syncFlush"><Property name="jetty.gzip.syncFlush" default="false" /></Set>
                <Set name="excludedAgentPatterns">
                    <Array type="String">
                        <Item><Property name="jetty.gzip.excludedUserAgent" deprecated="gzip.excludedUserAgent" default=".*MSIE.6\.0.*"/></Item>
                    </Array>
                </Set>

                <Set name="includedMethodList"><Property name="jetty.gzip.includedMethodList" default="GET" /></Set>
                <Set name="excludedMethodList"><Property name="jetty.gzip.excludedMethodList" default="" /></Set>

            </New>
        </Arg>
    </Call>
</Configure>

I don't get any errors in the logging, but jetty does not send the content-encoding: gzip headers.