public function buildForm(
  array $form,
  FormStateInterface $form_state
) {
  $node = \Drupal::routeMatch()->getParameter('node');
  $nid = $node->nid->value;
  
  // CHAMP DE TYPE TEXTE
  $form['name'] = [
    '#title'       => t('Name'),
    '#type'        => 'textfield',
    '#size'        => 50,
    '#description' => t("Your name."),
    '#required'    => True,
  ];
  
  // CHAMP DE TYPE EMAIL
  $form['email'] = [
    '#title'       => t('Email Address'),
    '#type'        => 'email',
    '#size'        => 25,
    '#description' => t("We'll send update to this address."),
    '#required'    => True,
  ];
  
  // BOUTON SUBMIT
  $form['submit'] = [
    '#type'        => 'submit',
    '#value'       => t('Save'),
  ];
  
  // CHAMP CACHÉ
  $form['nid'] = [
    '#type'        => 'hidden',
    '#value'       => $nid,
  ];
  
  return $form;
}