*
     * @return The set of property names.
     */
    public Set<String> getPropertyNames() {
        Set<String> propertyNames = new TreeSet<String>();
        propertyNames.addAll(declaredProperties.keySet());
        ClassMetaData superClass = getSuperClass();
        if (superClass != null) {
            propertyNames.addAll(superClass.getPropertyNames());
        }
        return propertyNames;
    }

            if (property == null) {
                throw new RuntimeException(String.format("No metadata for property '%s.%s'. Available properties: %s", classDoc.getName(), propName, classDoc.getClassMetaData().getPropertyNames()));
            }

            Map<String, ExtraAttributeDoc> additionalValues = new LinkedHashMap<String, ExtraAttributeDoc>();

            if (!superTypes.isEmpty()) {