How to force HSTS in Nexus 3 - jetty-9

Question

HSTS is not showing up as enabled in Nessus Scans on the port serving Nexus 3.16.1-02
Hello,
First time posting -
I'm trying to get HSTS enabled on Nexus OSS 3.16.1-02
From what I've read, this is enabled by default in the jetty-https.xml file for the application.
I've created an edited jetty-ssl.xml and added it to the /etc/jetty/ directory and the nexus.properties args for which xml files to call.
After rebooting the application and looking at the logs, everything looks good. The application is available, but Nessus scans for the HSTS vulnerability are still coming back positive.
The default https://localhost:443/nexus is currently configured behind an F5 reverse-proxy and HSTS is enabled on the F5, ssl is enabled in the application as well, terminating on port 443.
nexus.properties is calling for the jetty.xml,jetty-https.xml,jetty-ssl.xml,jetty-requestlog.xml when the application starts.
Any additional information on why this might coming up still would be greatly appreciated.
Thank you,
MCarrica
This is the nexus.properties
application-port-ssl=443
nexus-args=${jetty.etc}/jetty.xml,${jetty.etc}/jetty-ssl.xml,${jetty.etc}/jetty-https.xml,${jetty.etc}/jetty-requestlog.xml
nexus-context-path=/nexus
This is from the jetty-https.xml for the HSTS enabled
Arg><New class="org.eclipse.jetty.server.SecureRequestCustomizer"/></Arg>
Nessus scans are still showing HSTS is not enabled on port 443 on the server that is serving the application

Answer 1

Here are the contents of the rewrite.xml
<Configure id="Server" class="org.eclipse.jetty.server.Server">
<!-- =========================================================== -->
<!-- configure rewrite handler -->
<!-- =========================================================== -->
<Get id="oldhandler" name="handler"/>
<Set name="handler">
<New id="Rewrite" class="org.eclipse.jetty.rewrite.handler.RewriteHandler">
<Set name="handler"><Ref id="oldhandler"/></Set>
<Set name="rewriteRequestURI">true</Set>
<Set name="rewritePathInfo">true</Set>
<Set name="originalPathAttribute">requestedPath</Set>
<Call name="addRule">
<Arg>
<New class="org.eclipse.jetty.rewrite.handler.HeaderPatternRule">
<Set name="pattern">/*</Set>
<Set name="name">Strict-Transport-Security</Set>
<Set name="value">max-age=31536000; includeSubDomains</Set>
</New>
</Arg>
</Call>
</New>
</Set>
</Configure>