Authentication under Jetty in Eclipse - a problem with redeploy. How to decide?

Question

Eclipse

I am developing an application on GWT. I'm debugging it in Eclipse in DevMode, which in turn starts the Jetty server.
I decided to add user authentication to my application, and use the capabilities of Jetty for this. To do this, I wrote the following jetty-web.xml configuration file:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE Configure PUBLIC "-//Jetty//Configure//EN" "http://www.eclipse.org/jetty/configure.dtd">

<Configure class="org.eclipse.jetty.webapp.WebAppContext">
  <Get name="securityHandler">
    <Set name="loginService">
      <New class="org.eclipse.jetty.security.HashLoginService" id="DefaultLoginService">
            <Set name="name">Test Realm</Set>
            <Set name="config">realm.properties</Set>
            <Call name="start"/>
      </New>
    </Set>
    <Set name="checkWelcomeFiles">true</Set>
  </Get>

</Configure>

I created a realm.properties file, made a start page with login/password water fields, I launch it - everything works, users log in. But - when I try to re-deploy my application from eclipse to the server, I get an exception, after which the application becomes unavailable:

[WARN] Failed startup of context c.g.g.d.s.j.WebAppContextWithReload{/,file:/E:/workspace/WebApp1/WebContent/},E:\workspace\WebApp1\WebContent
java.lang.IllegalStateException: LoginService has different IdentityService to [email protected]
  at org.eclipse.jetty.security.SecurityHandler.doStart(SecurityHandler.java:354)
...

There is a feeling that when you re-deploy the LoginService is re-created and - something goes wrong (conflict with the previously created IdentityService?).
I could not find clear information on the syntax of jetty.xml, which would explain what an IdentityService is and how to configure it. Question - what to do? Does anyone have a working example of this file that can handle Jetty redeploy correctly?