Remove the redirect_method setting

  /**
   * {@inheritdoc}
   */
  public function defaultConfiguration() {
    return [
      'redirect_method' => 'post',
    ] + parent::defaultConfiguration();
  }

  mapping:
    redirect_method:
      type: string
      label: 'Redirect method'

Both of these were copied from the Commerce example module and can just be removed, since they're unused and unneeded.

Btw, you'll want to use snake_case consistently, you have a few camelCase variables (such as $customerProfile) around the module.