jetty-webapp-verifier/src/test/resources/servlet_level_2.4.config.xml

<?xml version="1.0" encoding="UTF-8"?>

<Configure id="basicRuleSet"
  class="org.eclipse.jetty.webapp.verifier.RuleSet">
  <Set name="rules">
    <Array type="org.eclipse.jetty.webapp.verifier.Rule">
      <Item>
        <New class="org.eclipse.jetty.webapp.verifier.rules.ServletSupportLevelRule">
          <Set name="supportedVersion">2.1</Set>
        </New>
      </Item>
    </Array>
  </Set>
</Configure>