Backend\Modules\Analytics\Form\SettingsStepAuthConfigFileType::handle PHP Method

    public function handle()
    {
        $this->form->cleanupFields();
        if (!$this->form->isSubmitted() || !$this->isValid()) {
            return false;
        }
        $certificate = base64_encode(file_get_contents($this->form->getField('certificate')->getTempFileName()));
        $this->settings->set('Analytics', 'certificate', $certificate);
        $this->settings->set('Analytics', 'email', $this->form->getField('email')->getValue());
        return true;
    }