public function get_indicators() {
        if ($this->indicators !== null) {
            return $this->indicators;
        }

        $fullclassnames = json_decode($this->model->indicators);

        if (!is_array($fullclassnames)) {
            throw new \coding_exception('Model ' . $this->model->id . ' indicators can not be read');
        }

        $this->indicators = array();
        foreach ($fullclassnames as $fullclassname) {
            $instance = \core_analytics\manager::get_indicator($fullclassname);
            if ($instance) {
                $this->indicators[$fullclassname] = $instance;
            } else {
                debugging('Can\'t load ' . $fullclassname . ' indicator', DEBUG_DEVELOPER);
            }
        }

        return $this->indicators;
    }