public function init($configuration = null)
    {
        if ($this->isInitialized) {
            return;
        }

        // Calls the base class's constructor manually as this isn't done automatically.
        parent::__construct();

        $this->initializeConfiguration($configuration);
        $this->ensureContentObject();

        if ($this->extKey !== '') {
            $this->pi_setPiVarDefaults();
            $this->pi_loadLL();
            $this->initializeConfigurationCheck();
        }

        $this->isInitialized = true;
    }