ModulesUninstallForm::submitForm

public ModulesUninstallForm::submitForm(array &$form, FormStateInterface $form_state)

public function submitForm(array &$form, FormStateInterface $form_state) {
  // Save all the values in an expirable key value store.
  $modules = $form_state->getValue('uninstall');
  $uninstall = array_keys(array_filter($modules));
  $account = $this->currentUser()->id();
  // Store the values for 6 hours. This expiration time is also used in
  // the form cache.
  $this->keyValueExpirable->setWithExpire($account, $uninstall, 6 * 60 * 60);

  // Redirect to the confirm form.
  $form_state->setRedirect('system.modules_uninstall_confirm');
}