+ /**
+ * Add subplugin structure to any element in the activity backup tree
+ *
+ * @param string $subplugintype type of subplugin as defined in activity db/subplugins.php
+ * @param backup_nested_element $element element in the activity backup tree that
+ * we are going to add subplugin information to
+ * @param bool $multiple to define if multiple subplugins can produce information
+ * for each instance of $element (true) or no (false)
+ */
+ protected function add_subplugin_structure($subplugintype, $element, $multiple) {