private void addLoggingSpec(ModelElement loggingSpec, Admin admin) {
        if (loggingSpec == null) return;
        String componentSpec = loggingSpec.requiredStringAttribute("name");
        String levels = loggingSpec.requiredStringAttribute("levels");
        var levelSpec = new LevelsModSpec();
        levelSpec.setLevels(levels);
        admin.addLogctlCommand(componentSpec, levelSpec);
    }
A base class for admin model builders, to support common functionality across versions.

@author Ulf Lilleengen
@author Vegard Havdal
config-model/src/main/java/com/yahoo/vespa/model/builder/xml/dom/DomAdminBuilderBase.java