Issue #3391497: Time-related fields do not show their default values

"Content expiration" and "Date Time" fields on InputDemo form show current time as default value.

Closes #3391497

modules/form_api_example/src/Form/InputDemo.php

@@ -2,6 +2,7 @@
 
 namespace Drupal\form_api_example\Form;
 
+use Drupal\Core\Datetime\DrupalDateTime;
 use Drupal\Core\Extension\ModuleExtensionList;
 use Drupal\Core\Form\FormBase;
 use Drupal\Core\Form\FormStateInterface;
@@ -70,10 +71,11 @@ public function buildForm(array $form, FormStateInterface $form_state) {
     ];
 
     // Date.
+    $now = new DrupalDateTime();
     $form['expiration'] = [
       '#type' => 'date',
       '#title' => $this->t('Content expiration'),
-      '#default_value' => ['year' => 2020, 'month' => 2, 'day' => 15],
+      '#default_value' => $now->format('Y-m-d'),
       '#description' => 'Date, #type = date',
     ];
 
@@ -82,8 +84,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
       '#type' => 'datetime',
       '#title' => 'Date Time',
       '#date_increment' => 1,
-      '#date_timezone' => date_default_timezone_get(),
-      '#default_value' => date_default_timezone_get(),
+      '#default_value' => $now,
       '#description' => $this->t('Date time, #type = datetime'),
     ];