/**
     * Builds the extension meta-data for the given class.
     */
    public void build(ClassDoc classDoc) {
        Map<String, ClassExtensionDoc> plugins = new HashMap<String, ClassExtensionDoc>();
        for (MixinMetaData mixin : classDoc.getExtensionMetaData().getMixinClasses()) {
            String pluginId = mixin.getPluginId();
            ClassExtensionDoc classExtensionDoc = plugins.get(pluginId);