private Set<ComponentSpecification> read(Element spec, String attributeName) {
        Set<ComponentSpecification> componentSpecifications = new LinkedHashSet<>();

        componentSpecifications.addAll(spaceSeparatedComponentSpecificationsFromAttribute(spec, attributeName));

        return componentSpecifications;
    }
Build an Inheritance object from an inheritance section.
@author Tony Vaagenes
config-model/src/main/java/com/yahoo/vespa/model/builder/xml/dom/chains/InheritanceBuilder.java