public function feedback()
    {
        $adapterParams                = [];
        $adapterParams['certificate'] = $this->certificatePath;
        $adapterParams['passPhrase']  = $this->passPhrase;

        // Development one by default (without argument).
        /** @var PushManager $pushManager */
        $pushManager = new PushManager($this->environment);

        // Then declare an adapter.
        $apnsAdapter = new ApnsAdapter($adapterParams);

        $this->feedback = $pushManager->getFeedback($apnsAdapter);

        return $this->feedback;
    }