ModulesUninstallConfirmForm::buildForm

public ModulesUninstallConfirmForm::buildForm(array $form, FormStateInterface $form_state)

public function buildForm(array $form, FormStateInterface $form_state) {
  // Retrieve the list of modules from the key value store.
  $account = $this->currentUser()->id();
  $this->modules = $this->keyValueExpirable->get($account);

  // Prevent this page from showing when the module list is empty.
  if (empty($this->modules)) {
    drupal_set_message($this->t('The selected modules could not be uninstalled, either due to a website problem or due to the uninstall confirmation form timing out. Please try again.'), 'error');
    return $this->redirect('system.modules_uninstall');
  }

  $data = system_rebuild_module_data();
  $form['text']['#markup'] = '<p>' . $this->t('The following modules will be completely uninstalled from your site, and <em>all data from these modules will be lost</em>!') . '</p>';
  $form['modules'] = array(
    '#theme' => 'item_list',
    '#items' => array_map(function($module) use ($data) {
      return $data[$module]->info['name'];
    }, $this->modules),
  );

  // List the dependent entities.
  $this->addDependencyListsToForm($form, 'module', $this->modules, $this->configManager, $this->entityManager);

  return parent::buildForm($form, $form_state);
}