protected function postprocess_chunk($data) {

        // Iterate over all the data tags, if any of them is
        // not 'subplugin_XXXX' or has value, then it's a valid chunk,
        // pass it to standard (parent) processing of chunks.
        foreach ($data['tags'] as $key => $value) {
            if (trim($value) !== '' || strpos($key, 'subplugin_') !== 0) {
                parent::postprocess_chunk($data);
                return;
            }
        }
        // Arrived here, all the tags correspond to sublplugins and are empty,
        // skip the chunk, and debug_developer notice
        $this->chunks--; // not counted
        debugging('Missing support on restore for ' . clean_param($data['path'], PARAM_PATH) .
                  ' subplugin (' . implode(', ', array_keys($data['tags'])) .')', DEBUG_DEVELOPER);
    }