private function getPluginController($class)
    {
        if ($this->pluginControllers === null) {
            /** @noinspection PhpIncludeInspection */
            $this->pluginControllers = file_exists($this->pluginManifestOfControllers) ? include $this->pluginManifestOfControllers : [];
        }

        return isset($this->pluginControllers[$class]) && count($this->pluginControllers[$class]) == 1 ? $this->pluginControllers[$class][0] : null;
    }