getRedirectPath example

    $form['message'] = [
      '#type' => 'textarea',
      '#title' => $this->t('Message'),
      '#default_value' => $contact_form->getMessage(),
      '#description' => $this->t('The message to display to the user after submission of this form. Leave blank for no message.'),
    ];
    $form['redirect'] = [
      '#type' => 'path',
      '#title' => $this->t('Redirect path'),
      '#convert_path' => PathElement::CONVERT_NONE,
      '#default_value' => $contact_form->getRedirectPath(),
      '#description' => $this->t('Path to redirect the user to after submission of this form. For example, type "/about" to redirect to that page. Use a relative path with a slash in front.'),
    ];
    $form['reply'] = [
      '#type' => 'textarea',
      '#title' => $this->t('Auto-reply'),
      '#default_value' => $contact_form->getReply(),
      '#description' => $this->t('Optional auto-reply. Leave empty if you do not want to send the user an auto-reply message.'),
    ];
    $form['weight'] = [
      '#type' => 'weight',
      '#title' => $this->t('Weight'),