Drupal → Вывести дефолтное значение элемента формы с помощью #lazy_builder

Пример вывода текущей даты в textfield:

<?php

namespace Drupal\example_module\Form;

use Drupal\Component\Utility\Crypt;
use Drupal\Core\Form\FormBase;
use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\Security\TrustedCallbackInterface;

class ExampleForm extends FormBase implements TrustedCallbackInterface {

  /**
   * {@inheritDoc}
   */
  public function buildForm(array $form, FormStateInterface $form_state): array {
    /** @see \Drupal\Core\Form\FormBuilder::prepareForm:764 */
    $date_value_placeholder = 'form_date_placeholder_' . Crypt::hashBase64($this->getFormId());

    $form['date'] = [
      '#type' => 'textfield',
      '#title' => 'Date',
      '#default_value' => $date_value_placeholder,
      '#attached' => [
        'placeholders' => [
          $date_value_placeholder => [
            '#lazy_builder' => [
              [self::class, 'dateValueLazyBuilder'],
              [],
            ],
          ],
        ],
      ],
    ];

    return $form;
  }

  /**
   * {@inheritDoc}
   */
  public static function trustedCallbacks(): array {
    return [
      'dateValueLazyBuilder',
    ];
  }

  /**
   * Lazy builder callback.
   */
  public static function dateValueLazyBuilder(): array {
    return [
      '#markup' => date('r'),
    ];
  }

}