void addLoggingSpecs(ModelElement loggingElement, Admin admin) {
        if (loggingElement == null) return;
        for (ModelElement e : loggingElement.children("class")) {
            addLoggingSpec(e, admin);
        }
        for (ModelElement e : loggingElement.children("package")) {
            addLoggingSpec(e, admin);
        }
    }
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