DomExtension (DomExtensionsRegistrar registrar, DomGenericInfo elementInfo, String childName) { if (elementInfo.getCollectionChildDescription(childName) == null) { // register if not yet defined statically Class<? extends AntDomElement> modelClass = getModelClass(childName); if (modelClass == null) { modelClass = AntDomElement.class; } return registrar.registerCollectionChildrenExtension(new XmlName(childName), modelClass); } return null; }